Test system with a thermal head comprising a plurality of adapters for independent thermal control of zones

ABSTRACT

Disclosed herein are thermal heads and corresponding test systems for independently controlling a one or more components while testing one or more devices under test. In some embodiments, a thermal head comprises a plurality of adapters, one or more heaters, and one or more thermal controllers for independently controlling temperatures of the components. The thermal controllers may control the temperatures of at least some of the components independently such that thermal control of one component does not affect the thermal control of the other component. In some embodiments, the thermal control is by way of one or more cold plates, and the thermal head comprises one or more cold plates. Embodiments of the disclosure further include independent control of one or more forces using one or more force mechanisms.

FIELD

The present disclosure relates to a test system comprising a thermalhead capable of independently controlling a plurality of zones whiletesting a device.

BACKGROUND

Integrated circuit (IC) chips are typically fabricated with a pluralityof identical copies on a semiconductor wafer. After wafer fabricationhas been completed, the wafer may be cut or diced to separate theindividual IC chips. These IC chips (also referred to as a device) maythen be tested (referred to as a device under test (DUT)). The testingmay involve electrical testing (burn-in tests, open- and short-circuittests, device functional tests, system level tests, etc.), where theperformance (e.g., functionality, speed, reliability, etc.) of an ICchip may be measured by a test system to determine whether the IC chipmeets one or more performance metrics. For example, electrical testsignals may be communicated to and/or from the IC chip to measure itsperformance. If an IC chip meets the performance metrics, then it may beassembled into a package. The package may be used for multiple purposessuch as providing environmental protection and electrical contacts fromthe IC chip to a system board, among others. These packages may betested. In some instances, the testing at the package level is similarto the testing at the chip level.

The performance of a DUT may be compared to a target performance, suchas the performance of a reference device or another device, or accordingto a specification. One factor that may cause the performance of a DUTto deviate or fail prematurely while being tested may be itstemperature. To ensure that any deviations in the performance of a DUTis not due to temperature, the DUT's temperature may be controlledduring testing. It may be important that the temperature of the DUTremain constant and at a set point temperature (or within a givenrange). While under test, thermal energy may be exchanged between theDUT and components that are thermally coupled to it. A DUT's temperaturemay be controlled via a heatsink or cold plate that is thermally coupledto the DUT. Thermal coupling may occur when there is sufficient contactbetween the cold plate and the DUT and/or any intermediate layers.

Advances in technology, such as process nodes, have led to moredifficult and expensive wafer fabrication. For example, technologiesinvolving 9 nm or below may require extreme ultraviolet (EUV)fabrication techniques for critical mask layers. It may be difficult todesign and fabricate advanced types of IC chips (e.g., system-on-chip(SOC) at the wafer level), particularly when a multitude of functionsare involved. In some instances, different package designs may bedeveloped or utilized. For example, a plurality of IC chips, a bare mixof IC chips, pre-packaged IC chips, etc., may be packaged together intoa device. Different types of advanced packages, such assystem-in-package (SiP), multi-chip module (MCM), stacked die,heterogeneous integration package, etc., have already been developed andare becoming more complex structurally and functionally. In someinstances, the devices comprise an increasing number of components inthe same size or more compact packaging, causing the components to bewithin close proximity to each other. The close proximity may make itdifficult to control the temperatures of the components if not accountedfor, as the temperature of a component may be affected by thetemperature of a neighboring component.

Some of the devices (a chip or a package) may comprise a plurality ofzones, where each zone may comprise one or more components (e.g., ICchips that are components in a package may each comprise a zone). Forexample, a complex SOC may comprise a plurality of components such asgraphic processing unit (GPU) cores, a plurality of central processingunit (CPU) cores, and various interfaces and other functions, which aresegmented into a plurality of zones in the device. In some instances,the components in a device under test may have different properties suchas height, surface area, stacked vs. non-stacked, etc., and as such, atest system having a single adapter or a plurality of adapters with thesame properties may not sufficiently thermally couple to the components(e.g., due to insufficient contact). In some instances, the componentsmay dissipate different amounts of power while under testing conditionsdue to different functions of and/or tests being performed on the zones.It may be beneficial to keep the temperature of the components constantand at the same set point temperature (or within a given range) whilethe device is being tested. A test system may not account for thedifferent amounts of power dissipation. What is needed is a test systemcapable of independent control of one or more properties (e.g.,temperature, applied force, movement, etc.) for different components ina device or devices under test. What is needed is a test system capableof independently controlling components that are within close proximityto each other.

SUMMARY

Disclosed herein are thermal heads and corresponding test systems forindependently controlling a plurality of zones (e.g., one or morecomponents) while testing one or more devices under test. In someembodiments, a thermal head comprises a plurality of adapters, one ormore heaters, and one or more thermal controllers for independentlycontrolling temperatures of the components. For example, two componentsmay have different set point temperatures. The thermal controllers maycontrol the temperatures of the two components independently such thatthermal control of one component does not affect the thermal control ofthe other component. At a given time, a first heater (thermally coupledto the first component) may be heating the first component, while thetemperature of the second component may remain the same. In someembodiments, the thermal control is by way of one or more cold plates,and the thermal head comprises one or more cold plates. As onenon-limiting example, at a given time, a first component is being cooledby a cold plate, whereas the second component is not. As yet anotherexample, a third component may not be thermally coupled to a heaterand/or cold plate. Embodiments of the disclosure include independentcontrol of one or more forces using one or more force mechanisms.

A test system for testing one or more devices under test is disclosed.The test system comprises: a thermal head for controlling one or moretemperatures of the one or more devices under test, the thermal headcomprising: a plurality of adapters thermally coupled to one or morecomponents of the one or more devices under test; and one or moreheaters thermally coupled to the plurality of adapters and the one ormore components of the one or more devices under test, wherein the oneor more heaters are configured to heat the one or more components of theone or more devices under test; and one or more thermal controllersconfigured to independently control the one or more temperatures of theone or more components of the one or more devices under test.Additionally or alternatively, in some embodiments, at least two of theone or more components have different set point temperatures.Additionally or alternatively, in some embodiments, the one or moretemperatures of the one or more components are independently controlledusing different changes in temperature. Additionally or alternatively,in some embodiments, the one or more heaters comprise a first heater anda second heater and the one or more components comprise a firstcomponent and a second component, wherein the first heater is configuredto heat the first component, and the second heater is configured to heatthe second component. Additionally or alternatively, in someembodiments, the thermal head further comprises one or more temperaturesensors configured to measure temperatures of the one or more heaters orthe plurality of adapters, wherein the one or more thermal controllerscontrol the one or more temperatures based on the measured temperatures.Additionally or alternatively, in some embodiments, an update frequencyof the one or more thermal controllers for independently controlling theone or more temperatures of the one or more components is less than 200microseconds. Additionally or alternatively, in some embodiments, theone or more heaters comprise a heater including at least two heatingelements, wherein the thermal head further comprises: a thermalinsulator located between the at least two heating elements.Additionally or alternatively, in some embodiments, the thermalinsulator comprises a material having through-holes or trenches.Additionally or alternatively, in some embodiments, the thermal headfurther comprises: a thermal interface material located on at least oneside of at least one of the one or more heaters. Additionally oralternatively, in some embodiments, the thermal head further comprises:a thermal interface material located on at least one side of at leastone of the plurality of adapters. Additionally or alternatively, in someembodiments, the plurality of adapters comprises a first adapterthermally coupled to a first thermal interface material layer and asecond adapter thermally coupled to a second thermal interface materiallayer, wherein a thermal resistance of the first thermal interfacematerial layer is different from a thermal resistance of the secondthermal interface material layer. Additionally or alternatively, in someembodiments, the first thermal interface material layer has a greatersurface area than the second thermal interface material layer.Additionally or alternatively, in some embodiments, the second thermalinterface material layer comprises openings or holes. Additionally oralternatively, in some embodiments, at least one of the one or moreheaters contacts at least one of the one or more components.Additionally or alternatively, in some embodiments, at least one of theone or more heaters is attached to at least one of the plurality ofadapters. Additionally or alternatively, in some embodiments, the atleast one heater comprises a plurality of pins that allow the at leastone heater to attach to the at least one adapter. Additionally oralternatively, in some embodiments, the plurality of pins is attached tothe at least one adapter by soldering, welding, brazing, press fitting,or conductive adhesive. Additionally or alternatively, in someembodiments, a surface area of at least one of the one or more heatersis the same as a surface area of a corresponding adapter. Additionallyor alternatively, in some embodiments, at least one of the one or moreheaters and a corresponding adapter comprise mating alignment featuresfor aligning the at least one heater and the corresponding adapter.Additionally or alternatively, in some embodiments, the one or morecomponents of the one or more devices under test comprise a firstcomponent and a second component, and the plurality of adapterscomprises a first adapter and a second adapter, wherein the firstcomponent is thermally coupled to the first adapter and the secondcomponent is thermally coupled to the second adapter. Additionally oralternatively, in some embodiments, the one or more thermal controllerscontrol the one or more temperatures of the one or more components basedon amounts of power from the one or more components. Additionally oralternatively, in some embodiments, the amounts of power from the one ormore components comprise amounts of expected power dissipation.Additionally or alternatively, in some embodiments, the thermal headfurther comprises: one or more cold plates thermally coupled to at leastone of the plurality of adapters, wherein the one or more cold platesare configured to cool the at least one adapter. Additionally oralternatively, in some embodiments, the one or more cold plates areindependently controlled. Additionally or alternatively, in someembodiments, the thermal head further comprises: one or more forcemechanisms configured to apply force to at least one of the one or morecomponents. Additionally or alternatively, in some embodiments, the oneor more force mechanisms are independently controlled. Additionally oralternatively, in some embodiments, at least two of the one or morecomponents have different heights. Additionally or alternatively, insome embodiments, at least one of the plurality of adapters is thermallycoupled to at least two of the one or more components. Additionally oralternatively, in some embodiments, each of the plurality of adapters isthermally coupled to a unique one of the one of the one or morecomponents. Additionally or alternatively, in some embodiments, the oneor more components are part of a single device under test.

A test system for testing one or more devices under test is disclosed.The test system comprises: a thermal head for controlling one or moretemperatures of the one or more devices under test, the thermal headcomprising: a plurality of adapters thermally coupled to one or morecomponents of the one or more devices under test; and one or more coldplates thermally coupled to the plurality of adapters, wherein the oneor more cold plates are configured to cool the plurality of adapters;and one or more thermal controllers configured to independently controlthe one or more temperatures of the one or more components of the one ormore devices under test. Additionally or alternatively, in someembodiments, at least two of the one or more components have differentset point temperatures. Additionally or alternatively, in someembodiments, the one or more temperatures of the one or more componentsare independently controlled using different changes in temperature.Additionally or alternatively, in some embodiments, the one or more coldplates comprise a first cold plate and a second cold plate, and theplurality of adapters comprise a first adapter and a second adapter,wherein the first cold plate is configured to cool the first adapter andthe second cold plate configured to cool the second adapter.Additionally or alternatively, in some embodiments, at least two of theplurality of adapters are thermally coupled to the same cold plate.Additionally or alternatively, in some embodiments, at least one of theplurality of adapters contacts at least one of the one or more coldplates. Additionally or alternatively, in some embodiments, the at leastone cold plate has a surface area that is the same as a surface area ofthe at least one adapter. Additionally or alternatively, in someembodiments, the one or more thermal controllers set, adjust, ormaintain temperatures of the one or more cold plates by setting,adjusting, or maintaining a flow rate or temperature of a liquid or agas associated with the one or more cold plates. Additionally oralternatively, in some embodiments, an update frequency of the one ormore thermal controllers for independently controlling the one or moretemperatures of the one or more components is less than 200microseconds. Additionally or alternatively, in some embodiments, thethermal head further comprises: a thermal interface material located onat least one side of at least one of the one or more cold plates.Additionally or alternatively, in some embodiments, the thermal headfurther comprises: a thermal interface material located on at least oneside of at least one of the plurality of adapters. Additionally oralternatively, in some embodiments, the plurality of adapters comprise afirst adapter thermally coupled to a first thermal interface materiallayer and a second adapter thermally coupled to a second thermalinterface material layer, wherein a thermal resistance of the firstthermal interface material layer is different from a thermal resistanceof the second thermal interface material layer. Additionally oralternatively, in some embodiments, the first thermal interface materiallayer has a greater surface area than the second thermal interfacematerial layer. Additionally or alternatively, in some embodiments, thesecond thermal interface material layer comprises openings or holes.Additionally or alternatively, in some embodiments, the one or morecomponents of the one or more devices under test comprise a firstcomponent and a second component and the plurality of adapters comprisea first adapter and a second adapter, wherein the first component isthermally coupled to the first adapter and the second component isthermally coupled to the second adapter. Additionally or alternatively,in some embodiments, the one or more thermal controllers control the oneor more temperatures of the one or more components based on amounts ofpower from the one or more components. Additionally or alternatively, insome embodiments, the amounts of power from the one or more componentscomprise amounts of expected power dissipation. Additionally oralternatively, in some embodiments, at least two of the one or morecomponents have different amounts of power dissipation. Additionally oralternatively, in some embodiments, the thermal head further comprises:one or more heaters thermally coupled to at least one of the one or morecomponents, wherein the one or more heaters are configured to heat theat least one component. Additionally or alternatively, in someembodiments, the one or more heaters are independently controlled.Additionally or alternatively, in some embodiments, the thermal headfurther comprises: one or more force mechanisms configured to applyforce to at least one of the one or more components. Additionally oralternatively, in some embodiments, the one or more force mechanisms areindependently controlled. Additionally or alternatively, in someembodiments, the one or more force mechanisms contact at least one ofthe one or more cold plates. Additionally or alternatively, in someembodiments, at least one of the plurality of adapters is thermallycoupled to at least two of the one or more components. Additionally oralternatively, in some embodiments, each of the plurality of adapters isthermally coupled to a unique one of the one of the one or morecomponents. Additionally or alternatively, in some embodiments, the oneor more components are part of a single device under test.

A test system for testing one or more devices under test is disclosed.The test system comprises: a thermal head for controlling one or moretemperatures of the one or more devices under test, the thermal headcomprising: a plurality of adapters thermally coupled to one or morecomponents of the one or more devices under test; and one or more forcemechanisms configured to apply one or more forces to the one or morecomponents of the one or more devices under test; and a force controllerconfigured to independently control the one or more forces applied tothe one or more components of the one or more devices under test.Additionally or alternatively, in some embodiments, at least two of theone or more components are tested with different applied forces.Additionally or alternatively, in some embodiments, the one or moreforce mechanisms comprise one or more force applicators that apply theone or more forces to the one or more components. Additionally oralternatively, in some embodiments, the one or more force applicatorscomprise: a pneumatic or hydraulic cylinder, a pneumatic or hydraulicdiaphragm, a stepper motor, a linear motor, a server motor, anelectroactive polymer actuator, a shape memory alloy actuator, anelectromagnetic actuator, a rotary motor, an electromechanical actuator,a piezoelectric actuator, or a voice coil. Additionally oralternatively, in some embodiments, the one or more force mechanismscomprise one or more pushers, wherein the one or more force applicatorspush the one or more pushers such that the one or more devices undertest are moved toward a socket. Additionally or alternatively, in someembodiments, at least one of the one or more force mechanisms applies aforce greater than 2 kgf. Additionally or alternatively, in someembodiments, the one or more force mechanisms comprise a first forcemechanism and a second force mechanism, and the plurality of adapterscomprises a first adapter and a second adapter, wherein the first forcemechanism applies a first force to the first adapter and the secondforce mechanism applies a second force to the second adapter.Additionally or alternatively, in some embodiments, the one or moreforce mechanisms comprise one or more transducers configured to measureforces, wherein the force controller sets, adjusts, or maintains the oneor more applied forces based on the measured forces. Additionally oralternatively, in some embodiments, the one or more force mechanismscomprise one or more force applicators, wherein the one or more forceapplicators are controlled based on differences between the measuredforces and target forces. Additionally or alternatively, in someembodiments, the one or more transducers comprise: a pneumatic loadcell, a hydraulic load cell, an inductive load cell, a capacitive loadcell, a magnetorestrictive device, a strain gauge-based sensor, a forcesensitive resistor, a thin film device, or a piezoelectric device.Additionally or alternatively, in some embodiments, the thermal headfurther comprises: one or more cold plates, wherein the one or moretransducers contact the one or more cold plates. Additionally oralternatively, in some embodiments, at least one of the one or moreforce mechanisms comprises a spring. Additionally or alternatively, insome embodiments, at least one of the one or more force mechanismscomprises a piston, a ramp, and a roller, wherein movement of the pistoncauses movement of the ramp, which adjusts an amount of force applied bythe roller. Additionally or alternatively, in some embodiments, at leastone of the one or more force mechanisms comprises a cam and a roller,wherein rotation of the cam adjusts an amount of force applied by theroller. Additionally or alternatively, in some embodiments, at least oneof the one or more forces is a variable force that is different at thebeginning of the test and during the test, or during the test and at theend of the test. Additionally or alternatively, in some embodiments, atleast one of the one or more forces is a fixed force that is the same atthe beginning of the test and during the test, or during the test and atthe end of the test. Additionally or alternatively, in some embodiments,at least one of the one or more force mechanisms applies force to atleast two of the one or more components. Additionally or alternatively,in some embodiments, the test system further comprises: a testing forcemechanism configured to move the one or more devices under test towardsa socket for electrically coupling the one or more devices under test tothe socket. Additionally or alternatively, in some embodiments, thetesting force mechanism comprises a force applicator configured to applya force greater than 10 kgf. Additionally or alternatively, in someembodiments, the thermal head further comprises: one or more heatersthermally coupled to at least one of the one or more components, whereinthe one or more heaters are configured to heat the at least onecomponent. Additionally or alternatively, in some embodiments, the oneor more heaters are independently controlled. Additionally oralternatively, in some embodiments, the thermal head further comprises:one or more cold plates thermally coupled to at least one of theplurality of adapters, wherein the one or more cold plates areconfigured to cool the at least one adapter. Additionally oralternatively, in some embodiments, the one or more cold plates areindependently controlled. Additionally or alternatively, in someembodiments, the one or more thermal controllers control the one or moretemperatures of the one or more components based on amounts of powerfrom the one or more components. Additionally or alternatively, in someembodiments, the amounts of power from the one or more componentscomprise amounts of expected power dissipation. Additionally oralternatively, in some embodiments, at least two of the one or morecomponents have different amounts of power dissipation. Additionally oralternatively, in some embodiments, at least two of the one or morecomponents have different heights. Additionally or alternatively, insome embodiments, at least one of the plurality of adapters is thermallycoupled to at least two of the one or more components. Additionally oralternatively, in some embodiments, each of the plurality of adapters isthermally coupled to a unique one of the one of the one or morecomponents. Additionally or alternatively, in some embodiments, the oneor more components are part of a single device under test.

A test system for testing one or more devices under test is disclosed.The test system comprises: a thermal head for controlling one or moretemperatures of the one or more devices under test, the thermal headcomprising: a plurality of adapters thermally coupled to one or morecomponents of the one or more devices under test, wherein the pluralityof adapters comprises a first adapter and a second adapter, and movementof the first adapter is independent from movement of the second adapter;and a controller configured to independently control one or moreproperties of the plurality of adapters. Additionally or alternatively,in some embodiments, the one or more properties comprise temperature orforce. Additionally or alternatively, in some embodiments, the pluralityof adapters comprises a first adapter having a first height and a secondadapter having a second height. Additionally or alternatively, in someembodiments, the plurality of adapters comprises a first adapter havinga first thermal mass and a second adapter having a second thermal mass.Additionally or alternatively, in some embodiments, the plurality ofadapters comprises a first adapter having a first surface area thermallycoupled to a corresponding one or more components and a second adapterhaving a second surface area thermally coupled to corresponding one ormore components. Additionally or alternatively, in some embodiments, atleast two of the plurality of adapters are configured to thermallycouple to the one or more components on the same side of a substrate ofthe one or more devices under test. Additionally or alternatively, insome embodiments, at least two of the plurality of adapters areconfigured to thermally couple to the one or more components ondifferent sides of a substrate of the one or more devices under test.Additionally or alternatively, in some embodiments, the plurality ofadapters comprises a first adapter nested within a second adapter.Additionally or alternatively, in some embodiments, the plurality ofadapters comprises a first adapter and a second adapter, wherein thethermal head further comprises: a first heater thermally coupled to thefirst adapter and a second heater thermally coupled to the secondadapter, wherein the first heater is nested within the second heater.Additionally or alternatively, in some embodiments, the plurality ofadapters comprises a first adapter and a second adapter, wherein thethermal head further comprises: a first thermal interface material layerthermally coupled to the first adapter and a second thermal interfacematerial layer thermally coupled to the second adapter, wherein thefirst thermal interface material layer is nested within the secondthermal interface material layer. Additionally or alternatively, in someembodiments, the first adapter is thermally coupled to a first componentand the second adapter is thermally coupled to a second component, andwherein movement of the second component is not independent frommovement of the first component. Additionally or alternatively, in someembodiments, the one or more components comprise stacked components.Additionally or alternatively, in some embodiments, the first adapter isthermally coupled to a first component of the stacked components and thesecond adapter is thermally coupled to a second component of the stackedcomponents, wherein a height of the first adapter is less than a heightof the second adapter. Additionally or alternatively, in someembodiments, the first adapter is thermally coupled to a first componentof the stacked components and the second adapter is thermally coupled toa second component of the stacked components, wherein a force applied bythe first adapter is less than a force applied by the second adapter.Additionally or alternatively, in some embodiments, the thermal headfurther comprises: one or more heaters thermally coupled to at least oneof the one or more components, wherein the one or more heaters areconfigured to heat the at least one component. Additionally oralternatively, in some embodiments, the one or more heaters comprise afirst heater coupled to a first adapter and a second heater coupled to asecond adapter, wherein movement of the first heater is independent frommovement of the second heater. Additionally or alternatively, in someembodiments, at least one of the one or more heaters contacts at leastone of the plurality of adapters. Additionally or alternatively, in someembodiments, the one or more heaters are independently controlled.Additionally or alternatively, in some embodiments, the thermal headfurther comprises: one or more cold plates thermally coupled to at leastone of the plurality of adapters, wherein the one or more cold platesare configured to cool the at least one adapter. Additionally oralternatively, in some embodiments, the one or more cold plates comprisea first cold plate coupled to a first adapter and a second cold platecoupled to a second adapter, wherein movement of the first cold plate isindependent from movement of the second cold plate. Additionally oralternatively, in some embodiments, at least one of the one or more coldplates contacts at least one of the plurality of adapters. Additionallyor alternatively, in some embodiments, the one or more cold plates areindependently controlled. Additionally or alternatively, in someembodiments, the thermal head further comprises: one or more forcemechanisms configured to apply one or more forces to at least one of theone or more components. Additionally or alternatively, in someembodiments, the one or more force mechanisms are independentlycontrolled. Additionally or alternatively, in some embodiments, at leasttwo of the one or more components have different set point temperatures.Additionally or alternatively, in some embodiments, at least two of theone or more components have different amounts of power dissipation.Additionally or alternatively, in some embodiments, at least two of theone or more components are tested with different applied forces.Additionally or alternatively, in some embodiments, at least two of theone or more components have different heights. Additionally oralternatively, in some embodiments, at least one of the plurality ofadapters is thermally coupled to at least two of the one or morecomponents. Additionally or alternatively, in some embodiments, the oneor more components are part of a single device under test.

It will be appreciated that any of the variations, aspects, features,and options described in view of the systems and methods apply equallyto the methods and vice versa. It will also be clear that any one ormore of the above variations, aspects, features, and options can becombined. It should be understood that the invention is not limited tothe purposes mentioned above, but may also include other purposes,including those that can be recognized by one of ordinary skill in theart.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A illustrates a top view of an example chip comprising a pluralityof zones.

FIG. 1B illustrates a block diagram of an example test system, accordingto some embodiments.

FIG. 2A illustrates a top view of an example device comprising aplurality of zones, according to some embodiments.

FIG. 2B illustrates a cross-sectional view of the device along line A-A,as drawn in FIG. 2A.

FIG. 2C illustrates a cross-sectional view of the device along line B-B,as drawn in FIG. 2A.

FIGS. 3A-3C illustrate cross-sectional views of an example thermal headcomprising a plurality of adapters, according to some embodiments.

FIG. 4 illustrates a cross-sectional view of a portion of a thermalhead, according to some embodiments.

FIG. 5A illustrate a cross-section diagram of an example heater,according to some embodiments.

FIG. 5B illustrates an example adapter comprising a hole that providesaccess to a pin, according to some embodiments.

FIGS. 6A and 6B illustrate cross-section diagrams of an example coldplate, according to some embodiments.

FIG. 7A illustrates an example thermal interface material comprisingopenings or holes, according to some embodiments.

FIG. 7B illustrates an example liquid thermal interface material that isdispensed, according to some embodiments.

FIGS. 8A and 8B illustrate top and cross-sectional views, respectively,of a device including stacked components, according to some embodiments.

FIG. 9A illustrates a top view of an example device comprising stackedcomponents, according to some embodiments.

FIGS. 9B and 9C illustrate cross-sectional views of a thermal head anddevice, along line B-B and A-A, respectively, as drawn in FIG. 9A.

FIGS. 10A and 10B illustrate top and cross-sectional views,respectively, of an example device comprising components on a pluralityof sides of a substrate, according to some embodiments.

FIG. 11 illustrates a cross-sectional view of a part of a test systemcomprising a thermal head and a device under test having components on aplurality of sides of a substrate, according to some embodiments.

FIG. 12A illustrates an example force mechanism comprising a piston andramp, according to some embodiments of the disclosure.

FIG. 12B illustrates an example force mechanism comprising a cam-roller,according to some embodiments of the disclosure.

FIG. 13A illustrates a cross-sectional view of an example test system,according to some embodiments.

FIG. 13B illustrates a flowchart of an example method of operating thetest system 1390, according to some embodiments.

FIG. 14 illustrates an example active thermal control for a plurality ofcomponents of a device, according to some embodiments.

FIG. 15 illustrates an example thermal head and socket, according tosome embodiments.

FIG. 16 illustrates a block diagram of an exemplary computer used forone or more controllers, according to embodiments of the disclosure.

It will be appreciated that any of the variations, aspects, features,and options described in view of the systems apply equally to themethods and vice versa. It will also be clear that any one or more ofthe above variations, aspects, features, and options can be combined.

DETAILED DESCRIPTION

Disclosed herein are thermal heads and corresponding test systems forindependently controlling a plurality of zones (e.g., one or morecomponents) while testing one or more devices under test. In someembodiments, a thermal head comprises a plurality of adapters, one ormore heaters, and one or more thermal controllers for independentlycontrolling temperatures of the components. For example, two componentsmay have different set point temperatures. The thermal controllers maycontrol the temperatures of the two components independently such thatthermal control of one component does not affect the thermal control ofthe other component. At a given time, a first heater (thermally coupledto the first component) may be heating the first component, while thetemperature of the second component may remain the same. In someembodiments, the thermal control is by way of one or more cold plates,and the thermal head comprises one or more cold plates. As onenon-limiting example, at a given time, a first component is being cooledby a cold plate, whereas the second component is not. As yet anotherexample, a third component may not be thermally coupled to a heaterand/or cold plate. Embodiments of the disclosure include independentcontrol of one or more forces using one or more force mechanisms.Embodiments of the disclosure further include methods for operationthereof.

The following description is presented to enable a person of ordinaryskill in the art to make and use various embodiments. Descriptions ofspecific devices, techniques, and applications are provided only asexamples. These examples are being provided solely to add context andaid in the understanding of the described examples. It will thus beapparent to a person of ordinary skill in the art that the describedexamples may be practiced without some or all of the specific details.Other applications are possible, such that the following examples shouldnot be taken as limiting. Various modifications in the examplesdescribed herein will be readily apparent to those of ordinary skill inthe art, and the general principles defined herein may be applied toother examples and applications without departing from the spirit andscope of the various embodiments. Thus, the various embodiments are notintended to be limited to the examples described herein and shown, butare to be accorded the scope consistent with the claims.

Various techniques and process flow steps will be described in detailwith reference to examples as illustrated in the accompanying drawings.In the following description, numerous specific details are set forth inorder to provide a thorough understanding of one or more aspects and/orfeatures described or referenced herein. It will be apparent, however,to a person of ordinary skill in the art, that one or more aspectsand/or features described or referenced herein may be practiced withoutsome or all of these specific details. In other instances, well-knownprocess steps and/or structures have not been described in detail inorder to not obscure some of the aspects and/or features described orreferenced herein.

In the following description of examples, reference is made to theaccompanying drawings which form a part hereof, and in which it is shownby way of illustration specific examples that can be practiced. It is tobe understood that other examples can be used and structural changes canbe made without departing from the scope of the disclosed examples.

The terminology used in the description of the various describedembodiments herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used in thedescription of the various described embodiments and the appendedclaims, the singular forms “a,” “an,” and “the” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise. It will also be understood that the term “and/or” as usedherein refers to and encompasses any and all possible combination of oneor more of the associated listed items. It will be further understoodthat the terms “includes,” “including,” “comprises,” and/or“comprising,” when used in this specification, specify the presence ofstated features, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps, operations, elements, components,and/or groups thereof. It will also be understood that the term “same,”when used in this specification, refers to the stated feature as beingidentical or within a certain range (e.g., 1%, 5%, etc.) from identical.

Some of the devices may comprise a plurality of zones, where each zonemay comprise one or more components (e.g., IC chips in a package orfunctional blocks in a chip). FIG. 1A illustrates a top view of anexample chip comprising a plurality of zones. Device 100 may comprisezones 117A, 117B, 117C, 117D, 119A, 119B, and 119C. For example, acomplex SOC device may comprise a plurality of graphic processing unit(GPU) cores, a plurality of central processing unit (CPU) cores, andvarious interfaces and other functions, where zones 119A, 119B, and 119Cmay be high-power zones (e.g., comprising GPU and/or CPU cores), andzones 117A, 117B, 117C, and 117D may be low-power zones (e.g.,comprising memory, transceivers, etc.). A zone may comprise one or morecomponents. In some embodiments, at least two zones of a device maydissipate different amounts of power while under testing conditions dueto different functions of and/or tests being performed on the zones. Itmay be beneficial to keep the temperature of one or more zones constantand at one or more set point temperatures (or within a given range)while the device is being tested.

A zone may comprise one or more components, such as zone 117A comprisingone component, and zone 119C comprising at least two components. One ormore components may be part of a single device (as shown in the figure),or alternatively, part of a plurality of devices under test (not shownin the figure).

FIG. 1B illustrates a block diagram of an example test system, accordingto some embodiments. Test system 190 may comprise a thermal head 150, acontroller 158, a socket 121, and a tester 141. The thermal head 150 maybe configured to thermally control the device under test 100. Thethermal head 150 may comprise one or more of: an adapter 130, a heater156, a cold plate 162, or a force mechanism 132. The adapter 130 may beconfigured to allow thermal energy to transfer to and/or fromthermally-coupled components. For example, the adapter 130 may allowthermal energy (e.g., heat) to transfer from the heater 156 located onthe bottom side of the adapter 130 to the cold plate 162 located on thetop side of the adapter 130. The heater 156 may be configured to raisethe temperature (e.g., heat) of the device 100, and the cold plate 162may be configured to lower the temperature (e.g., cool) of the device100. The thermal head's ability and speed at thermally controlling thetemperature of the device 100 may depend on the thermal coupling betweenits components and the device 100.

The force mechanism 132 may be configured to apply a force to the device100 to enhance the thermal coupling between the thermal head 150 and thedevice 100. The controller 158 may be configured to send one or moresignals to the thermal head 150 to control one or more of itscomponents. For example, the controller 158 may send a current orvoltage signal to the heater 156 to cause it to heat the device 100. Asanother example, the controller 158 may send a current or voltage signalto a valve metering the flow inside the cold plate 162 or associatedchiller to cause it to cool down the device 100. Additionally oralternatively, the controller 158 may send a current or voltage signalto cause the force mechanism 132 to apply more or less force to thethermal head 150, thereby improving the thermal coupling between thethermal head 150 and the device 100 without damaging it. As onenon-limiting example, the thermal controller may be a field-programmablegate array (FGPA)-based proportional-integral-derivative (PID)controller.

The socket 121 may be configured to electrically couple powerconnections and/or test signals from the tester 141 to the device 100,or from the device 100 to the tester 141. The tester 141 may send testsignals and/or receive response signals for determining the performanceof the device 100. In some embodiments, the tester 141 may monitor thepower being supplied to one or more of: the DUT, a component, or zonesof the DUT. Although the figure illustrates the test system 190 ascomprising one or more components, embodiments of the disclosure mayinclude additional components, or one or more components may not beincluded. Additionally or alternatively, although one configuration ofthe test system is shown, embodiments of the disclosure may compriseother configurations such as the thermal head comprising an additionaladapter located on the bottom side of the device 100.

Example Thermal Head Comprising a Plurality of Adapters

FIG. 2A illustrates a top view of an example device comprising aplurality of zones, according to some embodiments. Device 200 maycomprise a plurality of components, such as component 202A, component202B, and components 203A-H mounted on a substrate 210. The device 200may comprise one or more high-power components (e.g., components 202),one or more low-power components (e.g., components 203), or acombination thereof. In some embodiments, the device 200 may compriseany type of component (e.g., chips or packages); non-limiting examplesinclude logic, RF, analog, digital, power, diodes (e.g., light emittingdiodes (LEDs)), sensors (e.g., image sensors), microelectromechanicalsystems (MEMS), integrated passive devices (IPDs), power managementunits or integrated circuits (PMUs, PMICs), etc. Additionally oralternatively, the device 200 may comprise other types of componentsincluding, but not limited to, resistors, capacitors, inductor,transistors, etc.

As one non-limiting example, the device 200 may be a SiP device used forhigh performance computing (HPC) applications. Component 202A andcomponent 202B may be processor chips (e.g., CPU and/or GPU chips)surrounded by dynamic random access memory (DRAM) chips, for example.The memory chips may be individual chips, packaged chips,through-silicon via (TSV) stacked chips (e.g., high bandwidth memory(HBM) devices), or the like. In some embodiments, one or more componentsmay be located in close proximity to one or more other components. Forexample, memory chips may be placed close to the processor chips toreduce signal delays and noise in the memory to processorinterconnections, improving overall performance due to, e.g., highertransfer speeds and reduced latency. The close proximity may cause thetemperature from one component to affect the temperature of anothercomponent.

FIG. 2B illustrates a cross-sectional view of the device 200 along lineA-A, as drawn in FIG. 2A. Line A-A may be drawn through components 202B,203D, and 203H. The components 202B, 203D, and 203H may be mounted onand connected to the substrate 210 by way of interconnects 206. In someembodiments, the components in a device 200 may be on a single layer ofthe substrate 210. In some embodiments, the interconnects 206 may becomponent interconnects, such as solder balls, copper pillar bumps, C4(controlled collapse chip connection) bumps, gold bumps, wire bonding,or conductive adhesive, as non-limiting examples. The interconnects 206may allow the components to be mechanically and/or electricallyconnected to the substrate 210. The substrate 210 may comprise any typeof material, such as laminate. In some embodiments, the substrate 210may comprise one or more layers of: conductive traces, conductive planelayers, dielectric layers, or a combination thereof. One or more viasmay be used to connect conductive layers. The layer(s) and/or vias maybe formed using a printed circuit board process. Embodiments of thedisclosure may include other materials (e.g., ceramic, silicon, glass,molding compound, etc.) for creating the substrate 210.

The components 202/203 and interconnects 206 may be located on the topside of the substrate 210, and interconnects 216 may be located on thebottom side of the substrate 210. In some embodiments, no components maybe located on the bottom side of the substrate 210. The interconnects216 may be, for example, used to electrically couple the device 200 to aboard. The board may be a test board, when the device 200 is beingtested, or a system board, when the device is being used in a finalproduct. When coupled to a test board, the interconnects 216 mayelectrically couple to a socket used to send test signals between atester and the device 200. The interconnects 216 may be solder balls,pins, leads, pads on the substrate 210, or other forms of interconnects.

As one non-limiting example, the test board may send one or more test(input) signals to the device 200 and/or may receive one or more outputsignals from the device 200. The test signal(s) may have a predeterminedpattern. The output signal(s) may represent the electricalcharacteristics of the device 200 in response to applying the testsignal(s) to the device 200 while being tested. In some embodiments, thetesting may be performed using multiple sets of input and outputsignals, while operating the device 200 under the same or differentconditions (e.g., different temperatures).

FIG. 2C illustrates a cross-sectional view of the device 200 along lineB-B, as drawn in FIG. 2A. Line B-B may be drawn through components 202Aand 202B. In some embodiments, as shown in the figure, two or morecomponents (e.g., chips or packages) may have different heights due to,e.g., different designs and/or manufacturing variations. For example,component 202A may be shorter than component 202B, resulting in a heightdifference 220. In some embodiments, the height difference 220 may bedue to differences in the types of components. For example, memory chip203A may be taller than processor chip 202A. As another example,high-power chip 202B may be taller than high-power chip 202A. It is alsocontemplated that in instances where components 202A and 202B have thesame height, they may be located at different planes after assembly tothe substrate 210 due to differences in final solder size duringassembly (e.g., differences in solder ball compression duringsoldering).

If the height differences of the components in the device 200 are notaccounted for, the test system may not be able to adequately control thetesting conditions of the components of the device 100. For example, thetest system may have an adapter or associated heater that contacts thetop of component 202B, but not the top of component 202A, due to theheight difference 220. As a result, the test system may be thermallycoupled to the component 202B, but may not be adequately thermallycoupled to the component 202A. Such lack of thermal coupling may causeperformance problems when testing the component 202A. Example testsystems of the disclosure are capable of simultaneously testingdifferent components in one or more devices under test having differentset point temperatures. The thermal control of the different componentsis such that they have temperatures within a tolerance (such as 1%, 5%,etc.) from respective set point temperatures without compromising theperformance of the components. Additionally or alternatively, the testsystems of the disclosure are able to test device(s) comprising multiplecomponents having different heights at a given time without compromisingthermal performance.

Although FIGS. 2A-2C illustrate two components with eight othercomponents located along the sides of a substrate, embodiments of thedisclosure may include any number and/or arrangement of components.Additionally or alternatively, the components in a device may bearranged in any manner not shown in the figure.

Embodiments of the disclosure may include a test system comprising athermal head configured to thermally control one or more devices undertest. FIGS. 3A-3B illustrates cross-sectional views of an examplethermal head comprising a plurality of adapters, according to someembodiments. The thermal head 350 may be configured to test one or moredevices. The device may comprise component 302A, component 302B,component 303A, component 303D, substrate 310, interconnects 306, andinterconnects 316, which may have one or more properties similar tocomponent 202A, 202B, 203A, 203D, substrate 210, interconnects 206, orinterconnects 216, respectively.

The thermal head 350 may comprise a plurality of adapters 330A-330D.Adapters 330B and 330C may be located at the inner regions of thethermal head 350, and the adapters 330A and 330D may be located at theouter regions of the thermal head 350. Each adapter 330 may be thermallycoupled to a corresponding component of the device. In some embodiments,one or more (e.g., each) adapters may be thermally coupled to onecomponent. In some embodiments, a first adapter may be thermally coupledto a first component, and a second adapter may be thermally coupled to asecond component. Adapter 330A may be thermally coupled to component303A, adapter 330B may be thermally coupled to component 302A, adapter330C may be thermally coupled to component 302B, and adapter 330D may bethermally coupled to component 303D. In some embodiments, the number ofadapters used for testing a device may be the same as the number ofcomponents in a device. In some embodiments, at least one adapter may bethermally coupled to one or more (e.g., at least two) components. Forexample, an adapter may be thermally coupled to a first component and asecond component. In some embodiments, the number of adapters used fortesting a device may be less than the number of components in a device.

By being thermally coupled, the temperature of an adapter may affect thetemperature of a corresponding thermally-coupled component. In someembodiments, two or more adapters may be thermally independent from oneanother such that the temperature of one adapter and/or itscorresponding thermally-coupled component may not affect the temperatureof another adapter and/or its corresponding thermally-coupled component.For example, the adapter 330B may be thermally independent from theadapter 330C, resulting in the temperatures of the adapters and/orcorresponding thermally-coupled components not affecting each other. Insome embodiments, the adapters and/or thermally-coupled components maybe independently controlled, such as independently thermally controlled.

The independent control may comprise one or more of: independent thermalcontrol (e.g., using independent adapters, independent heaters,independent flow control, independent heat sinks. and/or independentcold plates), or independent force control (e.g., using independentforce mechanisms). In this manner, the test system may provide differentthermal control for different components of a device.

One or more properties of one or more adapters may be such thatdifferent properties (e.g., heights) of the components may be accountedfor such that the heat transfer between a thermal head and a componentmay not be compromised due to, e.g., the size of the component. Forexample, one or more properties (e.g., size, force, etc.) of the adapter330B may be different than one or more properties of the adapter 330C toaccount for the height difference between the component 302A and thecomponent 302B. In some embodiments, the size (e.g., height) of anadapter and/or associated components may be related (e.g., inverselyproportional) to the size of the corresponding thermally-coupledcomponent. As one non-limiting example, the height of adapter 330C maybe taller (compared to the adapter 330B) due to component 302B beingshorter (compared to the component 302A).

In some embodiments, first adapter 330B may have a first height andsecond adapter 330C may have a second height. This difference in heightmay account for height differences between corresponding components ofthe device(s) under test. In some embodiments, first adapter 330B mayhave a first thermal mass and second adapter 330C may have a secondthermal mass. The difference in thermal mass may account for differencesin thermal masses between corresponding heaters. In some embodiments,first adapter 330B may have a first surface area, and second adapter330C may have a second area. This difference in surface area may accountfor differences in surface area between corresponding components of thedevice(s) under test, or differences in thermal interface material (TIM)layers. The adapters may have other differences, such as differentthermal conductivities, widths, etc. In some embodiments, differences inthe adapters may lead to heating or cooling the components by differentamounts.

The multiple-adapter thermal head of the disclosure comprises amonolithic adapter that is thermally coupled to components of a deviceunder test. The monolithic adapter may be made of a continuous material.In some instances, the monolithic thermal head may comprise a monolithiccold plate, a monolithic heater, and/or a plurality of large-sizedheaters (greater than 900 mm², as one non-limiting example). An exampleadapter is described in more detail below.

As shown in the figure, the thermal head 350 may include one or moreheaters 356 thermally coupled to one or more adapters and one or morecomponents of one or more devices under test. For example, the adapter330B may be thermally coupled to a heater 356B, and the adapter 330C maybe thermally coupled to a heater 356C. The first heater 356B may beconfigured to heat the first component 302A, and the second heater 356Cmay be configured to heat the second component 302B. In someembodiments, two or more heaters 356 may be thermally independent fromeach other such that the thermal control of one and/or its correspondingthermally-coupled component may not affect the thermal control ofanother heater 356 and/or its corresponding thermally-coupled component.In some embodiments, one or more (e.g., each) adapters may be thermallycoupled to a unique heater. In some embodiments, one or more adapters,such as the adapter 330A shown in FIG. 3A, may not be thermally coupledto a heater. Example heaters are discussed in more detail below.

A heater may be located close to a corresponding thermally-coupledcomponent so that the delay between the change in temperature of theheater and the change in temperature of the device may be minimized. Insome embodiments, at least one heater may be located adjacent to (e.g.,contacts) at least one component, or an intermediate layer (e.g., a TIMlayer) that contacts the component. In some embodiments, at least oneheater may be located adjacent to (e.g., contacts) at least one adapter.The at least one heater and the at least one adapter may comprise matingalignment features for aligning the two together. Any misalignments mayreduce the amount of thermal coupling between the heater and theadapter. Example mating alignment features may include, but are notlimited to, protrusions on one surface and mating indents on anothersurface, or the perimeter shape of one element (e.g., the heater) and acorresponding recess or outline in the adapter or a retainer.

Embodiments of the disclosure may include a heater comprising aplurality of (e.g., at least two) heating elements that are spatiallyseparated and thermally isolated using a thermal insulator between theheating elements. In some embodiments, a thermal insulator (e.g., athermal insulating material or air) may be located between at least twoheating elements to prevent or reduce thermal coupling between them.Example thermal insulating materials may include, but are not limitedto, materials having low thermal conductivity (e.g., polymers,plastics), materials having a high void content (e.g., foam materials,mineral wool), air, vacuum, or the like. In some embodiments, thethermal insulating material may comprise through-holes or trenches forincreased thermal isolation.

In some embodiments, a heater 356 may be a small-sized heater (less than500 mm², as one non-limiting example). Small-sized heaters may haveincreased complexity and/or manufacturing yields compared to large-sizedheaters. Small-sized heaters may also be easier to control due to theirlower thermal mass, particularly suitable for maintaining a device at orwithin a certain range from a set point temperature. In addition tobeing easier to control, small-sized heaters may operate faster (interms of temperature change), making thermal control of a device undertest more stable and accurate. In some embodiments, the size of a heatermay be based on the size of the component that it is thermally coupledto. For example, a device under test may comprise a plurality ofcomponents having different sizes, such as large-sized components andsmall-sized components, and the corresponding test system may comprise aplurality of heaters having different sizes, such as large-sized heatersand small-sized heaters. In some embodiments, the surface areas of thedevice and heater that contact each other may be the same. Anintermediate layer such as a TIM layer may also have the same surfacearea.

Additionally or alternatively, one or more TIM layers 322 may be used toenhance thermal coupling between an adapter and a correspondingcomponent of the thermal head or DUT. In some embodiments, a TIM layer322 may be located on at least one side of an adapter and/or a heater.The TIM layer 322 may be located between an adapter and a device (suchas TIM layer 322A located between adapter 330A and component 303A),between a heater and a device (such as TIM layer 322B located betweenheater 356B and component 302A), or between an adapter and a heater(such as TIM layer 332C located between adapter 330C and heater 356C).Additionally or alternatively, in some embodiments, a TIM layer may belocated between an adapter and a heater, and the same or a different TIMmay be located between the heater and a device (e.g., a TIM layer onboth sides of the heater). In some embodiments, different TIM layers mayhave different properties. For example, the thermal resistance of theTIM layer 322B may be different from the thermal resistance of the TIMlayer 322C. Example TIM layers are discussed in more detail below.

In some embodiments, one or more properties of the heater and/or TIM maybe configured to account for different sized components such that theheat transfer between a heater (or an adapter) and a component may notbe compromised due to the size of the component. Returning back to theprevious example of component 302A being taller than component 302B, insome embodiments, the height of the heater 356B and/or TIM layer 322Bmay be less than the height of the heater 356C and/or TIM layer 322C.

Embodiments of the disclosure may further include one or more forcemechanisms 332A or 332B to move a corresponding adapter closer to athermally-coupled component. Example force mechanisms may include, butare not limited to, a spring, a lever coupled to a force applicator, ora force applicator. In some embodiments, the force mechanism 332 mayapply a force onto one side of the adapter to move the other side closerto the surface of the TIM layer 322 and/or component. In someembodiments, movement of a first adapter is independent from movement ofa second adapter; for example, movement of adapter 330B may not causemovement of adapter 330C, and therefore movement of heater 356B may beindependent from movement of heater 356C. As one non-limiting example,the independent movement of the adapters may account for any heightdifferences (e.g., due to manufacturing tolerances). Embodiments of thedisclosure comprise test systems capable of independently controllingthe forces on different components.

The disclosed thermal head may comprise one or more controllers. Oneexample controller is a thermal controller configured to control one ormore heaters. A thermal controller may send one or more signals to agiven heater including, but not limited to, sending different signals todifferent heaters such that they are independently controlled. Forexample, a first signal sent to the first heater 356B may adjust itstemperature without affecting the second heater 356C. In someembodiments, at least two components may be tested at differenttemperatures during a given test operation, and correspondingcontrollers and heaters may operate independently to maintain thecomponents at those respective temperatures. For example, a firstcontroller and corresponding heater 356B may operate to insure the firstcomponent 302A is at a first temperature, while a second controller andcorresponding heater 356C may operate to insure the second component302B is at a second temperature.

In some embodiments, at least two components and corresponding heaters356 may have different changes in temperature. The at least twocomponents may have different power dissipation levels, for example, andas a result, different changes in temperature. For example, the firstcomponent 302A may dissipate a first power level, and the secondcomponent 302B may dissipate a second power level. The first heater 356Bmay operate at a first change in temperature corresponding to the firstpower level, while the second heater 356C may operate at a second changein temperature corresponding to the second power level. Additionally oralternatively, the thermal controller may control the temperature(s)based on power dissipated from the component(s) of one or more devicesunder test.

In some embodiments, two or more adapters may be thermally dependent,such that they are thermally coupled together. Two or more adapters(e.g., adapters 330A and 330D) may be coupled to the same inputs fromthe thermal controller. For example, the components 303A and 303D may below-power memory chips or packages arranged in a row of four, such asshown by the arrangement of components 203A-203D on the left side ofFIG. 2A or components 203E-203H on the right side. A single adapter or aplurality of adapters may be thermally coupled to plurality ofcomponents. In some embodiments, the plurality of adapters and/or theplurality of components may have the same height.

Additionally or alternatively, the controller may comprise a forcecontroller configured to send a plurality of signals to the thermal headto independently control one or more forces applied to one or morecomponents. The force controller may send one or more signals to a givenforce mechanism, such as sending different signals to different forcemechanisms to control the force applied by a given adapter. As onenon-limiting example, a force controller may cause a first force to beapplied to a first adapter 330B and a second force to be applied to asecond adapter 330C. For example, the force controller may apply alarger force to a component having a larger surface area compared to acomponent having a small surface area. In some instances, the pressureon the larger surface area component may be the same as the pressure onthe smaller surface area component.

In some embodiments, the thermal head 350 may comprise one or more coldplates configured to lower the temperature of one or more of: one ormore adapters, one or more components, or the device. FIG. 3Billustrates an example thermal head comprising a cold plate 362. In someembodiments, at least two of the plurality of adapters may be thermallycoupled to the same cold plate, such as adapter 330B and 330C beingthermally coupled to cold plate 362. Thermal energy may be transferredto/from the cold plate 362 to the adapter 330B and/or adapter 330C. Thecold plate 362 may be located on the top side of one or more adapters330, and one or more heaters 356 may be located on the bottom side ofthe adapter(s) 330. In some embodiments, the cold plate 362 can coolcomponents 303A and/or 303D by, e.g., contacting at least a part of theforce mechanisms 332A and/or 332B.

In some embodiments, the thermal head 350 may comprise a plurality ofcold plates, such as shown in FIG. 3C. At least two cold plates may bethermally independent from one another. Cold plate 362B may be thermallycoupled to the adapter 330B, and the cold plate 362C may be thermallycoupled to the adapter 330C. The thermal control of the cold plate 362Bmay not affect the temperature and/or thermal control of the cold plate362C and vice versa, for example.

In some embodiments, movement of cold plate 362B may be independent frommovement of cold plate 362C. The amount of force applied may depend onthe properties of the corresponding component, heater, TIM, adapter, ora combination thereof. More force may be applied when a correspondingcomponent has a larger surface area, for example. Example forcemechanisms are discussed in more detail below.

In some embodiments, at least two components and corresponding coldplates 362 may have different changes in temperature due to, e.g.,having different power dissipation levels. For example, the firstcomponent 302A may dissipate a first power level, and the secondcomponent 302B may dissipate a second power level. The first cold plate362B may operate with a first temperature corresponding to the firstpower level, while the second cold plate 362C may operate with a secondtemperature corresponding to the second power level. Additionally oralternatively, the cold plates 362B and 362C may operate at differenttemperatures, such as when the corresponding components are tested atdifferent temperatures.

The thermal controller may be configured to control one or more heaters(as discussed above), one or more cold plates, or both. To control thecold plate(s), the thermal controller may send one or more signals toone or more flow control valves associated with each cold plate. Ininstances where the thermal head comprises at least two cold plates, thethermal controller may send one signal to one cold plate's flow valvewithout affecting the flow through another cold plate's valve(independent flow control). The cold plate and associatedthermally-coupled components (adapter, heater, component, etc.) may bethermally isolated from other (e.g., neighboring) cold plates andassociated thermally-coupled components. In some embodiments, a thermalinsulator (e.g., a thermal insulating material or air) may be disposedbetween neighboring cold plates.

The properties of a cold plate 362 may be based on the properties of athermally-coupled adapter 330. For example, the surface area of the coldplate 362 (that contacts the adapter) may be the same as the surfacearea of the adapter 330 (the top side of the adapter that contacts thecold plate). As discussed in more detail below, a cold plate 362 maycomprise one or more cooling channels that a liquid or gas may flowthrough. The flow rate and/or temperature of the liquid or gas mayaffect the cooling abilities of the cold plate 362.

Example Thermal Head

Embodiments of the disclosure may include one or more thermal heads withthe properties as described herein. For purposes of simplifying thedescriptions, some of the figures may illustrate some, but not all,portions of the disclosed thermal heads. A portion of a thermal head,comprising an adapter, will now be described, but the thermal head mayinclude other portions not disclosed or in combination with thedisclosures herein. FIG. 4 illustrates a cross-sectional view of aportion of a thermal head, according to some embodiments. The thermalhead 450 is configured to thermally control a component 402 mounted on asubstrate 410. Although the figure illustrates a single adapter 430 andsingle component 402 on a single substrate 410, embodiments of thedisclosure may include any number of components (e.g., 2, 3, 4, 5, 10,etc.), any type of components (e.g., high-power chips, low-power chips,passive components, etc.), and any number of substrates.

When testing a device, it may be difficult, but important, to controlthe temperature of the device while being tested. In some instances,thermal control may require heating or cooling one or more components ofthe device at a rapid rate so that the component(s) may reach the setpoint temperature quickly and the temperature remains constant duringthe test.

The adapter 430 may comprise a continuous piece of thermally-conductivematerial. For example, the adapter 430 may comprise a metal such ascopper, aluminum, silver, or a metal matrix composite (copper-diamond,aluminum-diamond, copper-graphite, aluminum-graphite, etc.). One or moreproperties (e.g., thermal mass, height, surface area, etc.) may be basedon the set point temperature and/or the properties of thethermally-coupled heater and/or cold plate.

In some embodiments, the thermal head 450 may comprise a heater 456. Theheater 456 may be configured to apply heat to the component 402. In someembodiments, the heater 456 may increase the temperature of thecomponent 402 when, e.g., the component power is low and/or when itstemperature is lower than the set point temperature of the component402. The heater 456 may be any type of heater including, but not limitedto, a solid-state device (e.g., comprising a ceramic body with one ormore resistive traces), a cartridge heater in a thermally-conductivebody, a thermoelectric device (TED), a silicon-based semiconductordevice, etc. In some embodiments, the heater 456 may have a low thermalmass. In some embodiments, the thermal mass of the heater 456 may beless than the thermal mass of the adapter 430, the cold plate 462, orboth. In some embodiments, the thermal mass of the heater 456 may be atleast 5 times lower than the thermal mass of the adapter 430. In someembodiments, the thermal mass of the heater 456 may be at least 10 timeslower than the thermal mass of the adapter 430. The thermal mass of theheater 456 may affect its responsivity, temperature ramp rate, andconductive heat transfer, e.g., through the heater 456, adapter 430,cold plate 462, or a combination thereof.

Additionally or alternatively, the thermal head 450 may comprise coldplate 462. The cold plate 462 may be configured to cool the adapter 430,which may thereby cool the heater 456 and/or component 402. When theheater 456 is off, the cooled adapter 430 may cool the heater 456. Thecold plate 462 may include one or more cooling channels 469, which maycirculate liquid or gas to cool the cold plate 462. Example liquids mayinclude, but are not limited to, water, a heat transfer fluid, arefrigerant coolant, a gas, etc. In some embodiments, one or more othercooling mechanisms may be used to cool the cold plate 462, such as athermo-electric cooler (TEC) (as one non-limiting example). The TEC maycool the cold plate 462 below the temperature of a fluid circulatingthrough the cold plate 462, for example. As another (non-limiting)example, a chiller or a radiator may be used to cool the temperature ofthe fluid.

The adapter 430 may be configured to thermally couple to the component402. Better thermal coupling may lead to better thermal control. In someembodiments, thermal coupling may occur by way of the adapter 430 makingcontact with the component 402 and/or using one or more intermediatelayers to facilitate heat transfer between the adapter 430 and thecomponent 402. TIM layers 422 are example intermediate layers.

In some embodiments, one or more TIM layers 422 may be located betweenone or more components of the thermal head 450. A TIM layer 422 may beused to reduce thermal resistance, thereby enhancing the thermalcoupling. For example, one TIM layer 422 may be located between theadapter 430 and the heater 456, and/or one TIM layer 422 may be locatedbetween the heater 456 and the component 402. As another example, a TIMlayer 422 may be located between the cold plate 462 and the adapter 430(not shown). In some instances, a TIM layer may be excluded, andinstead, the cold plate 462 and adapter 430 may be one continuousmaterial (e.g., a cold plate with one or more adapters machined out ofits surface). A TIM layer may comprise one or more of: a thermal grease(e.g., oil or other material comprising embedded thermally-conductiveparticles such as metal particles or ceramic particles), a liquidmaterial (e.g., glycol, water), a carbon material, a metallic malleablematerial (e.g., a low-melting point material such as indium, tin, or acombination of materials such as a thermally conductive elastomeric padwith an aluminum foil cover layer), a thermally conductive elastomericpad, or the like.

In some embodiments, thermal coupling between the adapter 430 and thecomponent 402 may be improved when there is a force applied tocomponents of the thermal head 450 and/or the component 402, makingbetter contact. The thermal resistance between the adapter 430 and thecomponent 402 may be related to the amount of applied force. The appliedforce may also impact the contact between socket contactors andinterconnects 416 (which the test system uses to electrically connect tothe component). Additionally or alternatively, the applied force mayhelp prevent or reduce the component 402 and/or substrate 410 fromunwanted warping, which may lead to defects.

Embodiments of the disclosure may include other types of intermediatelayers including, but not limited to, bumps, posts, or other contactsover the surface of the adapter, cold plate, and/or heater to increaseor decrease thermal coupling. The number, size, density, and/or patternof the bumps, posts, or contacts may be configured such that a targetthermal resistance between an adapter and a heater, an adapter and acold plate, or a heater and a component may be obtained. In someembodiments, the thermal resistance may be configured according to thetype of component or device. For example, the test system for alow-power component may be configured with high thermal resistance. Alow-power heater may be used for thermal control, and due to the highthermal resistance, may be able to easily heat up the low-powercomponent.

The thermal head 450 may further comprise one or more temperaturesensors to measure the temperature of the adapter 430, heater 456, orcold plate 462. The measured temperature may be used by the thermalcontroller to set, adjust, or maintain the temperature of the adapter430, heater 456, and/or cold plate 462. The measured temperature may becompared to a set point temperature, and the signals sent to thecontroller may be updated accordingly to minimize the difference betweenthe measured temperature and the set point temperature. Setting,adjusting, or maintaining the temperature of the heater 456 may comprisesetting, adjusting, or maintaining the current or voltage from thethermal controller to the heater 456. Setting, adjusting, or maintainingthe temperature of the cold plate 462 may comprise setting, adjusting,or maintaining the flow rate or temperature of the liquid or gasassociated with the cold plate 462. In some embodiments, the updatefrequency of the thermal controller for controlling the temperatures isless than 200 microseconds.

An example method for controlling the temperature of a componentincludes, but is not limited to, setting or adjusting the temperaturebased on whether the measured temperature (e.g., heater temperature) isabove or below the set point temperature (or set point temperaturerange). If the measured temperature is above the set point temperature,the thermal controller reduces the amount of power to the heater. If themeasured temperature is below the set point temperature, then thethermal controller increases the amount of power to the heater. In someembodiments, the heater may be configured for a specific power output ofthe thermal controller. As one example, the thermal controller iscapable of powering the heater with up to 500 W using 100 V, where theheater generates 500 W with a 100 V supply (e.g., for the set pointtemperature or across the set point temperature range). In someembodiments, the heater may be configured for the correspondingcomponent, such as the heater having an output power that is greaterthan the output power of the component. For example, a 30 W heater maybe used to heat a 10 W component, while a 300 W heater may be used toheat a 100 W component. The lower the thermal mass of the heater, themore effective the heater 456 becomes in increasing the temperature ofthe component 402 quickly. In some embodiments, the thermal controllerseparately sets or adjusts different temperatures of the thermal head.For example, the controller sets or adjusts a DUT temperature, anadapter temperature, a cold plate temperature, etc.

Example Heater

FIG. 5A illustrate a cross-section diagram of an example heater,according to some embodiments of the disclosure. The figure illustratesone surface 558 of the heater 556, which contacts an adapter 530 or oneor more TIM layers (which would be located between the surface of theheater 556 and the adapter 530). Another surface 559 of the heater 556may contact a component of the DUT or a TIM layer (which would belocated between the surface 559 of the heater 556 and a component of theDUT).

In some embodiments, the heater 556 may comprise a plurality of heaterpins, one or more heating elements, one or more measurement traces, or acombination thereof. Some of the plurality of pins 551 (including pins551A and 551B), 553 (including pins 553A and 553B), 555 (including pins555A and 555B), and 557 (including pins 557A and 557B) may be pins usedto carry electrical current into and out of the heater 556. In someembodiments, the pins 551, 553, 555, and/or 557 may be attached to oneor more pads (not shown) on the heater 556. Example methods forattaching the heater pins to the pads include, but are not limited to,brazing, soldering, gluing (e.g., using electrically-conductive epoxy),etc. As shown in the figure, one or more insulating layers 566 mayinsulate the pins 551, 553, 555, and 557 from the adapter 530, e.g., toprevent electrical shorts. The insulating layers 566 may be locatedaround the heater pins, and/or between the heater pins and the adapter530. The insulating layers 566 may comprise one or more of: plastic,rubber, ceramic, or another dielectric. In some embodiments, aninsulating layer 566 may be a hollow polytetrafluoroethylene (PTFE) tubewith an inner diameter sized for the diameter of a heater pin and anouter diameter configured to fit into clearance holes in the body of theadapter 530.

Although FIG. 5A illustrates a single row of six heater pins,embodiments of the disclosure may comprise any configuration and numberof heater pins, such as a single row of heater pins arranged around theperimeter of the surface of the heater, two heater pins in a row on oneside of the heater, 10 or more heater pins in a row, 4 pins in two rowson two sides of the heater, or the like. In some embodiments, theplurality of heater pins may occupy less than 10%, 30%, 50%, etc. of thesurface 558 of the heater 556. In some embodiments, the inner region ofthe surface 558 of the heater 556 may exclude heater pins to allow theheater 556 to make contact with the adapter 530 at the inner region.

The heating elements 563 and 565 may be used to generate heat for theheater 556. In some embodiments, the heating elements 563 and 565 maycomprise resistors and/or resistive traces. The total area of thermalcontrol by the heater 556 may depend on the properties of the heatingelements 563 and 565. For example, the heating elements 563 and 565 maybe formed on separate layers within the body of the heater 556, whereone or more resistive traces of the heating element may be formed on aplurality of layers so that a target resistance within a target area ofthe heater 556 may be obtained. In some embodiments, the heatingelements 563 and 565 may be located closer to the adapter 530 than theground plane 567 and measurement trace 561.

In some embodiments, each zone of the thermal head may comprise one ormore heating elements and a measurement trace 561. In some embodiments,any number of heating elements and measurement traces may be associatedwith a zone, depending on the power requirements of the zone and powerlimitations of the heating elements. In some embodiments, the total areaof thermal control may be the same as the total surface area of theheater 556. Alternatively, the total area of thermal control may be less(e.g., 20%) than the total surface area of the heater 556. A heatingelement may be located throughout a large percentage (e.g., 80% or more)of the surface of the heater 556, or certain zone(s) of the heater 556.In some embodiments, one or more first heating elements may beassociated with one or more first zones, and one or more second heatingelements may be associated with one or more second zones. As onenon-limiting example, the first heating elements and first zones may behigh-power heating elements and high-power zones, respectively, whilethe second heating elements and second zones may be low-power heatingelements and low-power zones, respectively.

The heating elements 563 and 565 may be configured to generate heatusing, e.g., resistors. The heating elements may be electrically coupledto heater pins such that power via a current or voltage signal can beapplied to the heater pins to turn on the corresponding heatingelements. Power applied to pins 553A and 553B may cause theelectrically-coupled heating element 563 to turn on and generate heat,and power applied to pins 555A and 555B may cause theelectrically-coupled heating element 565 to turn on and generate heat.In some embodiments, the number of heating elements and/or heatingelement layers may be increased to increase the overall power outputfrom the heater 556 at a given voltage. For example, a heater 556 maycomprise five heating elements, each configured to generate 200 W at 200VDC, thereby generating a total output power of 1000 W.

In some embodiments, the heater 556 may comprise a plurality of heatingzones. In some embodiments, the heater 556 may comprise one or moreinsulating mechanisms to insulate two or more heaters or heating zonesfrom each other. One example insulating mechanism comprisesthrough-holes or trenches in the body of the heater at location(s)between the heating elements and edge(s) of the heating zones. Anotherexample insulating mechanism comprises using different adapters fordifferent zones, such as one or more first adapters and associatedheaters for a first heating zone, and one or more second adapters andassociated heaters for a second heating zone.

The measurement trace(s) 561 may be used for measuring the temperatureof one or more surfaces (e.g., the surface 559 that contacts a componentor an intermediate TIM layer) of the heater 556. The measurement trace561 may be located within the body of the heater 556. The measurementtrace 561 may be located close to the surface 559, for example. In someembodiments, the measurement trace 561 may be a trace with a certaintemperature coefficient of resistance such that its resistance can becorrelated to a temperature reading, this type of device is alsoreferred to as a resistance temperature detector (RTD).

In some embodiments, after manufacturing the heater 556, resistances ofthe measurement trace 561 can be measured at different temperatures togenerate pre-determined calibration information such as a calibrationcurve, calibration table, or associated relationships (betweenresistance and temperature). The pre-determined calibration informationmay be stored in, e.g., a non-volatile memory chip or coded into a 1D or2D code (e.g., a linear barcode or 2D matrix barcode) or stored remotelyin a database. The pre-determined calibration information may be used bya controller to determine the temperature of a heater or heat zone anduse that knowledge to control one or more resistors (e.g., resistor 563or resistor 565) included in the heater for thermal control of acorresponding zone.

In some embodiments, a measurement trace 561 may be coated with adielectric. The thickness of the dielectric may depend on the physicalconstruction and limitations of the heater 556. In some embodiments, thedielectric may have a thickness less than 2 mm. In some embodiments, thedielectric may have a thickness less than 0.4 mm. The measurement trace561 may be located throughout the surface 559 of the heater 556 thatcontacts a component or intermediate layer (e.g., a TIM layer thatcontacts the component). For example, the area in which the measurementtrace 561 is located may be the same as the area in which anotherheating element (e.g., resistor 563 or resistor 565) is located,although these may be on different layers in the heater.

While some of the plurality of pins may be used to carry electricalcurrent for heating, others may be used for shielding. Pins 557A and557B, shown in FIG. 5A, may be electrically coupled to a ground plane567 for electromagnetic interference (EMI) shielding. The ground plane567 may be grounded, providing an electrical ground path to the heater556 during testing. During testing, the heaters may be turned on and offin rapid succession, at high voltages and currents, which can generateelectrical noise that can potentially interfere with the testingcircuitry or measurements. Shielding the heater elements with a groundplane 567 that covers them may reduce or eliminate the unwantedelectrical noise. In some embodiments, the pins 557A and 557B may beelectrically coupled to an adapter. For example, as shown in the adapterillustrated in FIG. 5B, the adapter 530 comprises a hole 525 thatprovides access to the pin 557A and/or pin 557B. The hole 525 may exposeground pin 523 that may be attached to an adapter 530 by being, e.g.,soldered, spot welded, brazed, glued (e.g., using anelectrically-conductive adhesive), etc. In some embodiments, the pin557A and/or pin 557B may be attached to the adapter 530 by, e.g.,soldering. Having both the adapter 530 and ground plane 567 groundedimproves the shielding of the heater elements compared to having onlythe ground plane 567 grounded. In the case where both the adapter 530and ground plane 567 are grounded, there is an effective shield formedboth above and below the heater elements.

In some embodiments, the adapter may include a retainer 571. Theretainer 571 may be configured as a mechanical attachment for attaching(e.g., requiring a tool for removal) the heater 556 to the adapter 530.This mechanical attachment facilitates thermal coupling between theheater 556 and the adapter 530. Example mechanism attachments include,but are not limited to, clamps, screws, retains, or the like. As shownin the figure, the retainer 571 may be located within the body of theadapter 530, allowing the heater 556 and adapter 530 to have any sizesfor surface areas, including the same-sized surface area (as onenon-limiting example). With the size of the adapter being the same orsubstantially the same as the size of the corresponding component, thedisclosed test systems are able to quickly change the temperature of thecomponent due to, e.g., the thermal mass of the adapter. In someembodiments, the hole 525 in the adapter 530 provides access to one ormore pins, such as pins 557A and 557B.

Additionally or alternatively, the retainer 571 may be configured forelectrically coupling the adapter 530 to one or more ground pins 523.The ground pin 523 may be flexible ground pins, for example, that allowthe heater 556 and adapter 530 to expand at different rates. The heater556 and adapter 530 may have different coefficients of thermalexpansion, allowing the two to expand and contract at different rateswith temperature changes without undue stress or strain on eithercomponent and while maintaining good thermal contact between the adapter530 and the heater 556.

In some embodiments, the heater is attached (e.g., requires a tool forremoval) to the adapter. An attached heater results in better thermalcoupling between the adapter, heater, and/or any intermediate layers.Without attaching the heater, any movement in the adapter and/orintermediate layers may limit how quickly heat can transfer from theheater to the adapter and/or corresponding component.

Referring back to FIG. 5A, the ground plane 567 may be a solid groundplane or a perforated ground plane (the size of the perforations may beconfigured based on desired EMI frequencies). In some embodiments, thearea of the ground plane 567 may be greater than or equal to the area ofthe heating elements. In some embodiments, the area of the ground planemay be at least 80%, 85%, 90%, 95%, etc. of the area of the surface ofheater 556. The ground plane 567 may be located within a certain depthfrom the surface of the heater 556 (that contacts a component or anintermediate layer), such as (but not limited to) less than 1.5 mm, lessthan 1 mm, less than 0.6 mm, etc.

Although not shown in the figure, the heater 556 may comprise aplurality of dielectric layers, a plurality of conductive layers, and/ora plurality of conductive vias for making electrical connections betweenthe plurality of conductive layers. In some embodiments, the outersurfaces of the heater may comprise a protection layer (e.g., adielectric such as ceramic) to protect the conductive layers locatedwithin the heater 556.

Example Cold Plate

FIGS. 6A and 6B illustrate cross-section diagrams of an example coldplate, according to some embodiments of the disclosure. The cold plate662 may be oriented such that its bottom surface 691 is located closestto a corresponding heater or adapter. The cold plate 662 comprises acavity with an inlet and outlet for coolant 671 to circulate through thecooling channels 669. The cavity may be formed by a top plate 673 and abottom plate 675. The cold plate 662 comprises a plurality of fins 663.In some embodiments, the plurality of fins 663 may comprise fins thatare long, rectangular fins or rounded pin fins. The plurality of fins663 may be integrated into the bottom plate 675 and top plate 673. Insome embodiments, the plurality of fins 663 may be orientedperpendicular from the top plate 673 and/or bottom plate 675. Theplurality of fins 663 are used to increase the surface area thatcontacts the coolant 671 that flows through the cold plate 662, therebyproviding more effective heat transfer from the cold plate 662 to thecoolant 671.

Example Thermal Interface Material (TIM) Layers

The test system disclosed herein may use one or more TIM layers. A TIMlayer may affect the thermal resistance between an adapter and a heater,an adapter and a cold plate, an adapter and a component, or a heater anda component. A TIM layer may be selected based on one or more propertiesof the thermal head, adapter, heater, cold plate, a component on thedevice under test, etc. The thermal resistance may be adjusted byconfiguring the thickness of the TIM layer and/or its thermalconductivity, for example. Additionally or alternatively, the surfacearea of a TIM layer may be adjusted by including one or more openings orholes 727, as shown in FIG. 7A. The thermal resistance of the TIM layer722 may be configured based on size and/or number of openings or holes727. In some embodiments, the TIM layers 722 in a thermal head may bedifferent, e.g., a first TIM layer may have a greater surface area thana second TIM layer.

In some embodiments, the TIM layer 722 may be configured based on theproperties of the associated component and/or zone. For example, a highthermal resistance TIM layer may be used for a low-power component. Insome embodiments, the properties of the TIM layers may be different fordifferent components and/or zones of a device.

The TIM layer 722 may be formed using any technique, such as dispensinga liquid TIM 722 on a component or device, as shown in the example ofFIG. 7B. Using a liquid TIM may help minimize gaps between an adapterand a component, for example, which may reduce the thermal resistancebetween the two; although other types of TIM materials may be included,such as a solid TIM material, a paste TIM material, or a grease TIMmaterial. A reduced thermal resistance may be beneficial in instances,such as when an adapter does not comprise a heater, when an adapter isused only for cooling, when an adapter is used for adjusting thetemperature of a high-power component, or when an adapter comprises aheater and is used for both heating and cooling, among others.

A liquid TIM may be dispensed on the component(s) or device prior totesting and then removed after testing has been completed. To determinewhether the dispensed liquid TIM meets target properties (e.g., amount,location, thickness, etc. of the dispensed TIM), one or more techniquesmay be employed to inspect the dispensed liquid TIM, such as a machinevision system that visually inspects and compares it to one or morepre-determined criteria, or a system that tests its thermal resistancevalue. Based on whether or not the dispensed TIMs meet one or moretarget properties, the test system may proceed with performing the test(dispensed TIM qualifies), or create an alert (dispensed TIM does notqualify). In this manner, a device may be tested only when the TIMproperties do not affect the testing of the device, ensuring that thetesting results accurately represent the performance of the device. Toomuch dispensed liquid TIM may overflow onto one or more components andmay adversely affect it during testing (e.g., if the liquid TIM iselectrically conductive), or could pose a reliability issue for thedevice (e.g., if the liquid TIM induces corrosion or other deleteriouseffects). Too little TIM may lead to high thermal resistance(s), causingproblems with the testing such as being able to maintain the componentat a set point temperature. In some instances, if no TIM was dispensedand a high power is applied to the component, the component may fail dueto thermally-induced catastrophic failure.

Example Thermal Head for a Device Comprising Stacked Components

Embodiments of the disclosure may comprise other types of devices, suchas a device that may comprise one or more stacked components. FIGS. 8Aand 8B illustrate top and cross-sectional views, respectively, of adevice including stacked components, according to some embodiments. Thedevice 800 may include a plurality of components, such as component802B, component 802T, and components 803A-H mounted on a substrate 810.One or more components may be stacked on one or more other components,such as component 802T being a top component stacked on a bottomcomponent 802B. In some embodiments, the footprint of component 802T maybe smaller than the footprint of component 802B. Component 802B may be ahigh-power component, for example. In some embodiments, the stackedcomponents 802B and 802T may be coupled together using, e.g., one ormore interconnects 818 such as one or more of: TSVs, microbumps, or thelike. In some embodiments, components 803A-H may be auxiliarycomponents.

As one non-limiting example, the component 802T may be a cache memorychip, and the component 802B may be a processor chip, where thecomponent 802T may be stacked on the component 802B. In such anarrangement, the component 802T may be a standalone chip (e.g., a chipcapable of operating independently) that provides a higher memorycapacity than an internal cache in the processor chip itself. Stacking acache chip 802T on top of the processor chip 802B may reduceinterconnect length, thereby increasing read/write speeds and reducinglatency. In some embodiments, the component 802B may be a high-powercomponent, and the component 802T may be a low-power component.

Device 800 may further include substrate 810, interconnects 806, andinterconnects 816, where one or more of: the substrate 810,interconnects 806, or interconnects 816 have properties similar tocorresponding substrate 210, interconnects 206, or interconnects 216,respectively. As shown in FIG. 8B, there may be one or more heightdifferences among the stacked components (comprising components 802T and802B) and other components 803C and 803G in device 800.

The adapters of the thermal head may be configured such that heattransfer between an adapter (and/or heater and/or cold plate) andstacked components may not be compromised. FIG. 9A illustrates a topview of an example device comprising stacked components, according tosome embodiments. The device may comprise components 903A-903H.Additionally, the device 900 may comprise at least one stackedcomponent, which includes component 902T stacked on component 902B.Device 900 may have one or more properties (e.g., comprisinginterconnects to electrically couple components to a substrate,interconnects to electrically couple a substrate to a test system, etc.)similar to device 100, 200, 800, or a combination thereof.

FIGS. 9B and 9C illustrate cross-sectional views of a thermal head 950and device, along line B-B and A-A, respectively, as drawn in FIG. 9A.Thermal head 950 may comprise a first adapter 930B and/or a first heater956B that are thermally coupled to a first component (e.g., onecomponent 902B and/or lower portion of the stacked components) and asecond adapter 930C and/or second heater 956T thermally coupled to asecond component (e.g., component 902T and/or upper portion of thestacked components).

The test system may comprise a thermal head 950. The thermal head 950may comprise plurality of adapters including, but not limited to,adapters 930A-930D. One or more adapters, such as adapters 930A-930D mayhave one or more properties similar to other adapters disclosed herein,such as adapters 330A-330D. For example, the adapter 930A may not bethermally-coupled to a heater. As another example, the adapter 930D maytransfer force to a component applied by way of a spring or other forcemechanism 932F. The adapter 930D may additionally or alternatively becontacting a TIM layer 922F, located between the adapter 930D and thecomponent 903F.

In some embodiments, one or more adapters may be thermally coupled to afirst portion of the stacked components. For example, adapter 930B maybe thermally coupled to a component 902B or a portion of a component902B of the stacked components. The thermal coupling may comprise one ormore corresponding thermally-coupled components as making contact. Forexample, the adapter 930B may be thermally coupled to a heater 956B anda TIM 922B. The adapter 930B may contact the heater 956B, for example.The TIM 922B may contact a portion of the component 902B, such as itsouter region (e.g., outer perimeter).

Adapter 930C may be thermally coupled to another component (e.g.,component 902T) or another portion of the stacked components. Theadapter 930C may be thermally coupled to a heater 956T and a TIM 922C,where the TIM 922C may contact the top surface of the component 902T. Insome embodiments, the first adapter 930C may be nested (fully orpartially) within the second adapter 930B. The second adapter 930B maysurround a plurality (two or more, such as four) sides of the firstadapter 930C. The first adapter 930C and second adapter 930B may bethermally coupled, for example.

In some embodiments, the corresponding first heater 956T may be nestedwithin the second heater 956B. The second heater 956B may surround aplurality (e.g., two or four) sides of the first heater 956B. Similarly,the first TIM layer 922C may be nested within the second TIM layer 922B.In some embodiments, as shown in the figure, a TIM layer 922C may belocated between the components of the stacked components.

In some embodiments, the second adapter 930C may be located in a hollowportion of and surrounded by the first adapter 930B. In someembodiments, the first adapter 930B, the corresponding heater 956B,and/or the corresponding TIM 922B may contact most (e.g., more than 50%)of the top surface of the component 902B.

In some embodiments, thermal control of the first component 902B in thestacked components and/or its thermally-coupled (first) adapter 930B maybe independent from thermal control of the second component 902T in thestacked components and/or its thermally-coupled (second) adapter 930C.In some embodiments, separate control signals may be transmitted to thecorresponding heaters, cold plates, and/or force mechanisms.

The different adapters, heaters, and/or TIM layers for differentportions of the stacked components may be configured accordingly. Forexample, the force applied by the adapter 930C to both components in thestack (component 902B and component 902T) may be at least partiallytransferred as force applied to the bottom component (component 902B).The adapters may apply force to different regions of component 902B, soin some embodiments, the force applied by adapter 930C may be less thanthe force applied by the adapter 930B. As another example, the topcomponent 902T may a memory chip and the bottom component 902B may be aprocessor. The heater 956T for the top component 902T may be lesspowerful than the heater 956B for the bottom component 902B.Additionally or alternatively, the adapter 930C (contacting the topcomponent 902T, or an intermediate layer such as the heater 956T and/orTIM 922C) has a lower conductivity, smaller contact area, and/or higherTIM resistance compared to the adapter 930B (contacting the bottomcomponent 902B).

One or more (e.g., each) of the adapters, heaters, cold plates, and/orTIM layers disclosed herein of a given device may account fordifferences in the properties of the corresponding components, such asdifferent heights of the components and/or arrangement of components. Inthe example shown in FIGS. 9A-9C, adapter 930A, adapter 930D, adapter930E, and adapter 930F (and/or corresponding heaters, cold plates, TIMlayers, or a combination thereof) may account for the height(s) ofcomponent 903B, component 903F, component 903C, and component 903G,respectively, and any associated TIM layers and/or interconnects. Theadapter 930B, heater 956B, and/or TIM layer 922B may account for theheight of component 902B and any associated TIM layers and/orinterconnects. The adapter 930C, heater 956T, and/or TIM layer 922C mayaccount for the total height of components 902B and 902T and anyassociated TIM layers and/or interconnects. One or more force mechanismsmay be used to move a corresponding adapter, heater, and/or cold platecloser to a thermally-coupled component. For example, the thermal head950 may comprise a spring 932B that moves adapter 930A closer to thecomponent 903B and a spring 932F that moves adapter 930D and TIM 922Fcloser to the component 903F. Other force mechanisms may be usedincluding, but not limited to, a lever, a force applicator, or the like.

Example Thermal Head for a Device Comprising Components on a Pluralityof Sides of a Substrate

In some embodiments, a device under test may include component(s) and/orpackage(s) located on a plurality of sides of a substrate, such asdevice 1000 including components 1002A and 1002B located on the top sideof the substrate 1010, and component 1002C located on the bottom side ofthe substrate 1010, as shown in the top and cross-sectional views ofFIGS. 10A and 10B, respectively. The top view of FIG. 10A illustratesthe outline of component 1002C (located on the bottom side of thesubstrate 1010). As shown in the figures, in some embodiments, thecomponent 1002C may be located at different regions of the substrate1010 along the x- and y-axes than the components 1002A and 1002B. Insome embodiments, high-power component(s) may be located on one side ofthe substrate 1010 and low-power component(s) on the other side.Interconnects 1006 may be component or package interconnects that mountthe components to the substrate 1010. For example, interconnects 1006Amay mount the component 1002A to the top surface of the substrate 1010,interconnects 1006B may mount the component 1002B to the top surface ofthe substrate 1010, and interconnects 1006C may mount the component1002C to the bottom surface of the substrate 1010. In some embodiments,the device 1000 may include interconnects 1016 to electrically couplethe device 1000 to a board. The board may be a test board with a socketthat engages the DUT (when the device 1000 is being tested) or a systemboard (when the device is being used in a package).

Although the figures illustrate chips, packages, or other components asmounted on the surface of a substrate, embodiments of the disclosure maycomprise one or more components that are partially or fully enclosedwithin the substrate. For example, the device under test may be anembedded die or fan-out wafer-level type of package.

FIG. 11 illustrates a cross-sectional view of a part of a test systemcomprising a thermal head and a DUT having components on a plurality ofsides of a substrate, according to some embodiments. The device maycomprise components 1102A and 1102B located on the top side of substrate1110 and component 1102C located on the bottom side. The thermal headmay comprise a plurality of adapters 1130A, 1130B, and 1130C forindependent control of components 1102A, 1102B, and 1102C, respectively.

In some embodiments, the thermal head may comprise one or more adaptersconfigured to thermally couple to corresponding components from aplurality of sides of a substrate. The adapters 1130A and 1130B areconfigured to thermally couple from the top side of the substrate 1110,and the adapter 1130C is configured to couple from the bottom side ofthe substrate 1110. In some embodiments, the thermal coupling and/orcontact of the adapters to the plurality of sides of the substrate mayoccur simultaneously.

Additionally or alternatively, the test system 1190 may comprise one ormore mechanisms for electrically coupling to send and/or receive testsignals from the device. A socket body 1170 may comprise test contactpins 1172, which may contact and/or electrically couple to theinterconnects 1116 of the device. The properties of the adapters 1130A,1130B, and 1130C may have similar properties to the adapters discussedherein.

Embodiments of the disclosure may include any of the propertiesincluding those described herein, such as (but not limited to) thedevice comprising additional components not shown in the figure, one ormore adapters thermally coupled to a plurality of components, using apassive or active temperature control, using a passive or active forcemechanism, etc.

Example Force Mechanisms

One (non-limiting) example force mechanism may comprise a piston. FIG.12A illustrates an example piston, according to some embodiments of thedisclosure. The thermal head may comprise the force mechanism, anadapter 1230, a cold plate 1262, and a heater 1256.

A piston 1243 is coupled to a ramp 1204 and a roller 1205. The piston1243 may move in accordance with the amount of applied force. Forexample, movement of the piston 1243 to the right along the x-axiscauses the ramp 1204 to move, applying a greater amount of force on theroller 1205, which then applies a greater amount of force on the top ofthe thermal head may then cause an applied force to the component 1202.The amount of applied force may be measured by a transducer 1239.

In some embodiments, the piston 1243 and at least a portion of the ramp1204 may be located off to the side of the thermal head, creating anoverall shorter profile than if the force applicator were located on topof the thermal head. The piston 1243, ramp 1204, and/or roller 1205 maybe used and exchanged for a certain type of component, such as aspecific SiP DUT where a greater amount of force is desired (e.g., ahigh pin-count or ball-count SiP). The specific SiP DUT may be testedwithout having to change the rest of the test system by removing anyother force mechanism and replacing it. The other force mechanism may beattached or detached using screws, bolts, or attachment means.

Another example force mechanism comprises a cam-roller, such as the oneshown in FIG. 12B. The cam-roller comprises a cam 1207A and a roller1207B. The cam 1207A rotates in a certain direction, such as clockwise,where the rotation of the cam adjusts the amount of force to be appliedvia the roller 1207B in the z-direction.

In some embodiments, at least one force applied by the forcemechanism(s) may be a variable force, wherein the variable force may bedifferent at the beginning of a test (right when testing begins) andduring the test, or during the test and at the end of the test (rightwhen testing ends). In some embodiments, the variable force may be forcethat has been adjusted during the test. In some embodiments, the atleast one force may be a fixed force that is the same at the beginningof the test and during the test, or during the test and at the end ofthe test. Embodiments may include other types of force mechanisms;example force mechanisms are discussed below.

Example Test Systems

FIG. 13A illustrates a cross-sectional view of an example test system,according to some embodiments. The test system 1390 may comprise athermal head and a socket. The device may comprise a plurality ofcomponents 1302, 1303A, and 1303B mounted on a substrate 1310. Thesubstrate 1310 may comprise interconnects 1316 to electrically couple toa tester (not shown). The socket comprises a socket body 1318 comprisingtest contact pins 1317. Movement of the socket body 1318 towards thedevice or movement of the device towards the socket body 1318 may causethe test contact pins 1317 to electrically couple to the interconnects1316.

One of the force mechanisms included in the test system 1390 maycomprise a pusher 1331 and force applicator 1333 for electricallycoupling the device to the test contact pins 1317 of the test system1390 for testing (e.g., sending and/or receiving electrical signals fromthe tester to the device). The force applicator 1333 pushes the pusher1331, which then pushes one or more unpopulated portions of thesubstrate 1310 of the device towards the socket body 1318 andcorresponding test contact pins 1317. The force applicator 1333 can beany type of device that applies a force including, but not limited to, apneumatic or hydraulic cylinder, a pneumatic or hydraulic diaphragm, astepper motor, a linear motor, a server motor, an electroactive polymeractuator, a shape memory alloy actuator, an electromagnetic actuator, arotary motor, an electromechanical actuator, a piezoelectric actuator, avoice coil, or other active force application device. The forceapplicator 1333 may apply a force between 5-300 kgf, including any forcein between.

In some embodiments, the test system may comprise a transducer 1329 thatmeasures the force being applied by the force applicator 1333 inreal-time (while the force is being applied). The transducer 1329 cangenerate one or more force measurement signals used as feedback for acontroller communicating to the force applicator 1333 to adjust theforce applied such that a target force is met. The transducer 1329 cancomprise a pneumatic load cell, a hydraulic load cell, an inductive loadcell, a capacitive load cell, a magnetorestrictive device, a straingauge-based sensor, a force sensitive resistor, a thin film device, apiezoelectric device, or the like. Although the figure illustrates thetransducer 1329 as having a width that is the same as the pusher 1331,embodiments of the disclosure may include a transducer 1329 that has awidth smaller than the width of the pusher 1331. In some embodiments,the test system 1390 may comprise one or more springs (not shown) thatmay be used to return the pusher 1331, transducer 1329, and/or forceapplicator 1333 to a home position when the force applicator 1333 is notapplying a force. Additionally, in some embodiments, the test system1390 may comprise a home sensor (not shown) used to indicate when thepusher 1331, transducer 1329, and/or force applicator 1333 are in thehome position. The home position may be the position where the pusher1331, transducer 1329, and/or force applicator 1333 are located thefurthest away from the thermal head and/or not applying a force to it,for example.

Another force mechanism in the test system 1390 may comprise a forcemechanism included in a thermal head. The thermal head force mechanismmay comprise a force applicator 1343 for thermally coupling the deviceto the thermal head for thermal control of one or more components of adevice under test. The force applicator 1343 may apply force to a coldplate 1362 and/or an adapter 1330C of the thermal head. The forceapplicator 1343 can be any type of device that applies a forceincluding, but not limited to, a pneumatic or hydraulic cylinder,pneumatic or hydraulic diaphragm, stepper motor, linear motor, servermotor, voice coil, or other active force application device. The forceapplicator 1343 can apply a force including, but not limited to, between1 kgf, 2 kgf, 100 kgf, 300 kgf, or 500 kgf. The thermal head maycomprise a transducer 1339 (e.g., load cell, strain gauge-based sensor,force sensitive resistor, thin film device, piezoelectric device, or thelike) that measures the force being applied by the force applicator 1343in real-time and generates one or more force measurements signals usedas feedback for a controller communicating to the force applicator 1343to adjust the applied force to meet a target force. The force applicator1343 may have any width, for example, the same width or smaller than thewidth of the adapter 1330.

As shown with the example of FIG. 13A, embodiments of the disclosure maycomprise active thermal control, passive thermal control, active forcecontrol, passive force control, or a combination thereof. Active thermalcontrol may be used to set or change the temperature of one or morecomponents of a device to a set point temperature (or within a givenrange). The active thermal control may comprise a heater 1356, adapter1330C, and/or a cold plate 1362, which change the temperature of one ormore components in a device based on a thermal controller. A temperaturesensor may be included for measuring the temperature of the device undertest, where the measured temperature may be used as feedback by thethermal controller, heater 1356, and/or cold plate 1362.

Additionally or alternatively, the test system 1390 may comprise passivethermal control. Passive thermal control may allow one or morecomponents in a device to change its temperature using, e.g., heattransfer. The passive thermal control may comprise one or more adapters1330A and 1330B, which may transfer (e.g., exchange) thermal energy withone or more thermally-coupled components 1303A and 1303B, respectively.In some embodiments, the passive thermal control may allow thetemperature of a thermally-coupled component to reach the temperature ofthe adapter 1330. The adapters 1330A and 1330B may contact thecomponents 1303A and 1303B, respectively. In some embodiments, theadapters 1330A and 1330B (for passive thermal control) may not bethermally coupled to a heater. In some embodiments, one or more adapters1330A and/or 1330B may not be thermally coupled to a cold plate 1362 ormay be thermally coupled to a cold plate 1362 that does not includecooling channels for circulation of a cooling material.

Embodiments of the disclosure may include both active and passivethermal control. For example, as shown in the figure, the test systemmay comprise one or more adapters 1330A and 1330B for passive thermalcontrol and one or more adapters, such as adapter 1330C, for activethermal control. In some embodiments, active thermal control may be usedfor components that have temperature set points or specificrequirements, while passive thermal control may be used for other typesof components (e.g., low-power components, components that do not havespecific test temperature requirements, components whose performance isnot sensitive to temperature, etc.).

Additionally or alternatively, any type of thermal control may becombined with any type of force control. For example, one or moreadapters, such as adapters 1330A and 1330B for passive thermal controlmay be combined with passive force control, such as a spring, bellows,elastomer, or the like. As another example, a force applicator 1343 foractive force control may be combined with a heater 1356 for activethermal control.

In some embodiments, different amounts of control may be used to accountfor different temperature set points or requirements, differentcomponent heights, different arrangements, etc.

FIG. 13B illustrates a flowchart of an example method of operating thetest system 1390, according to some embodiments. Process 1370 comprisesstep 1372 where the test system 1390 sets the temperature of the thermalhead to one or more set point temperatures. The ramp rate of thetemperature may be as fast as possible or may be predetermined, forexample. In step 1374, the test system places the device to be tested ina socket. The temperature of the thermal head may reach the one or moreset point temperatures before or after the device is placed in thesocket.

In step 1376, a first force may be applied to the device forelectrically coupling the device to the socket. A transducer may measurethe amount of force applied. If the measured force does not meet athreshold force, then the test system may cease process 1370. Otherwise,in step 1378, a second force may be applied to the device in order tobring the adapter(s)/heater(s)/TIM(s) in contact with the individualchips, e.g., the force need to thermally couple the thermal head to thedevice. A transducer measures the amount of force applied to the device,and ends the process if it does not meet a threshold force.

If the amount of first force and the amount of second force applied tothe device meet their respective threshold forces, then the test system1390 starts device testing (step 1380). In some embodiments, the testsystem 1390 starts device testing in response to a start-of-test signaltransmitted from one or more controllers (e.g., a handler, a thermalcontroller). During the test, the test system 1390 may optionally sendone or more signals to the controller to change modes and/or set pointtemperature(s) (step 1382). Example modes may comprise, but are notlimited to, measuring the heater temperature, measuring the DUTtemperature, etc. The mode may be changed in accordance with theexamples of the disclosure.

In step 1384, the test system 1390 completes the device testing andsends an end-of-test signal to the controller(s). The second forceapplied on the device may be removed (step 1386), and then the firstforce applied on the device may be removed (step 1388). In someembodiments, process 1370 may not proceed to step 1388 until the testsystem 1390 verifies that the second force applied on the device hasbeen removed (in step 1386). In some embodiments, process 1370 may notproceed to step 1390 until the test system 1390 verifies that the firstforce applied on the device has been removed (in step 1388). In step1390, the device may be removed from the socket. One or more steps ofprocess 1370 may be repeated, e.g., to test other devices.

Embodiments of the disclosure may comprise active thermal control for aplurality of components of a device, as shown in FIG. 14 . The testsystem 1490 may comprise a thermal head and a socket. In someembodiments, the thermal head comprises a force mechanism. The forcemechanism (e.g., pusher 1431, transducer 1429, force applicator 1433,force applicator 1443, transducer 1439, etc.) and socket (comprisingsocket body 1418 and test contact pins 1417) may have one or moreproperties similar to the force mechanisms and socket discussed herein(e.g., described in the context of FIGS. 13 and 15 ). The device maycomprise a plurality of components 1403, 1402A, and 1402B mounted on asubstrate 1410. The substrate 1410 may comprise interconnects 1416 forreceiving and/or transmitting test signals to and/or from a tester.

The test system 1490 may comprise a plurality of adapters 1430A and1430B thermally coupled to component 1402A and component 1402B,respectively. The plurality of adapters 1430 may be thermally coupled todifferent heaters 1456; adapter 1430A is thermally coupled to heater1456A, while adapter 1430B is thermally coupled to heater 1456B. Theplurality of adapters 1430 may be thermally coupled to different coldplates 1462; adapter 1430A is thermally coupled to cold plate 1462A,while adapter 1430B is thermally coupled to cold plate 1462B. A thermalcontroller may be configured to independently control the temperaturesof the component 1402A and component 1402B by way of the respectiveadapter 1430A or 1430B, heater 1456A or 1456B, and/or cold plate 1462Aor 1462B. These may be two non-limiting examples of active thermalcontrol.

Embodiments of the disclosure may further comprise passive thermalcontrol. The thermal energy dissipated from the component 1403 may beallowed to transfer (e.g., dissipate) heat to adapter 1430C.

Additionally or alternatively, the thermal head of FIG. 14 may compriseboth active and passive force control. For active force control, a forceapplicator 1443 applies force to the adapters 1430A and 1430B, whichthen applies force to components 1402A and 1402B. The amount of forceapplied, as measured by the transducer 1439, may be controlled by acontroller that determines the force to be applied by the forceapplicator 1443. In some embodiments, the force control may not beindependent for each adapter or component, such as the force applicator1443 applying force to at least two adapters and/or components.

Embodiments of the disclosure my further comprise passive force control.The spring 1432A may apply a force to the adapter 1430C, which thenapplies force to the component 1403. The amount of force applied may notbe adjustable and may be based on the properties of the spring 1432A.

Embodiments of the disclosure may comprise active force control for aplurality of components, according to some embodiments of thedisclosure. The test system 1590 of FIG. 15 may comprise a thermal headand a socket. The force mechanisms (e.g., pusher 1531, transducer 1529,force applicator 1533, force applicators 1543A and 1543B, transducer1539A and 1539B), other parts of the thermal head (e.g., cold plates1562A and 1562B, adapters 1530A, 1530B, and 1530C, heaters 1556A and1556B), socket (comprising socket body 1518 and test contact pins 1517),and parts of the device (e.g., interconnects 1516, components 1502A,1502B, and 1503, substrate 1510) may have one or more properties similarto the force mechanisms, parts of the socket, and parts of the devicediscussed herein (e.g., described in the context of FIGS. 13A and 14 ).

Example Controller

As discussed above, one or more controllers may be used for the testsystems and/or thermal heads of the disclosures. FIG. 16 illustrates ablock diagram of an exemplary computer 1602 used for one or morecontrollers, according to embodiments of the disclosure. The computermay be a machine, within which a set of instructions, causes the machineto perform any one of the methodologies discussed herein, may beexecuted, according to embodiments of the disclosure. In someembodiments, the machine can operate as a standalone device or may beconnected (e.g., networked) to other machines. In a networkedconfiguration, the machine may operate in the capacity of a server or aclient machine in a server-client network environment, or as a peermachine in a peer-to-peer (or distributed) network environment. Themachine can be a personal computer (PC), a tablet PC, a set-top box(STB), a personal digital assistant (PDA), a cellular telephone, a webappliance, a network router, a switch or bridge, or any machine capableof executing a set of instructions (sequential or otherwise) thatspecify actions to be taken by that machine. A mobile device may includean antenna, a chip for sending and receiving radio frequencytransmissions and wireless communications, and a keyboard. Further,while only a single machine is illustrated, the term “machine” shallalso be taken to include any collection of machines that individually orjointly execute a set (or multiple sets) of instructions to perform anyone of the methodologies discussed herein.

The exemplary computer 1602 includes a processor 1604 (e.g., a centralprocessing unit (CPU), a graphics processing unit (GPU), or both), amemory 1606 (e.g., read-only memory (ROM), flash memory, dynamic randomaccess memory (DRAM) such as synchronous DRAM (SDRAM), etc.), and astatic memory 1608 (e.g., static random access memory (SRAM), etc.),which can communicate with each other via a bus 1610.

The computer 1602 may further include a video display 1612 (e.g., aliquid crystal display (LCD) or light emitting diode (LED) display). Thecomputer 1602 also includes an alpha-numeric input device 1614 (e.g., akeyboard), a cursor control device 1616 (e.g., a mouse), a disk driveunit 1618, a signal generation device, a network interface device 1622,and one or more wireless interface devices.

The computer 1602 may also include other inputs and outputs, includingdigital I/O and/or analog I/O. For example, the inputs and outputs maycommunicate with external devices, such as chillers, pressurecontrollers, force controllers, flow value controllers, etc., using anytype of communication protocol.

The drive unit 1618 includes a machine-readable medium 1620 on which isstored one or more sets of instructions 1624 (e.g., software) embodyingany one or more of the methodologies or functions described herein. Thesoftware may also reside, completely or at least partially, within themain memory 1606 and/or within the processor 1604 during executionthereof by the computer 1602, the main memory 1606 and the processor1604 also constituting machine-readable media. The software may furtherbe transmitted or received over a network via the network interfacedevice 1622 and/or a wireless device.

While the machine-readable medium 1620 is shown in an exemplaryembodiment to be a single medium, the term “machine-readable medium”should be taken to include a single medium or multiple media (e.g., acentralized or distributed database and/or associated caches andservers) that store the one or more sets of instructions. The term“machine-readable medium” shall also be taken to include any medium thatis capable of storing, encoding, or carrying a set of instructions forexecution by the machine and that cause the machine to perform any oneor more of the methodologies of the present invention. The term“machine-readable medium” shall accordingly be taken to include, but notbe limited to, solid-state memories, optical and magnetic media, andcarrier wave signals.

Although examples of this disclosure have been fully described withreference to the accompanying drawings, it is to be noted that variouschanges and modifications will become apparent to those skilled in theart. Such changes and modifications are to be understood as beingincluded within the scope of examples of this disclosure as defined bythe appended claims.

The invention claimed is:
 1. A test system for testing one or moredevices under test, comprising: a thermal head for controlling one ormore temperatures of the one or more devices under test, the thermalhead comprising: a plurality of adapters thermally coupled to aplurality of components of the one or more devices under test; and aplurality of heaters thermally coupled to the plurality of adapters andthe plurality of components of the one or more devices under test,wherein the plurality of heaters are configured to heat the plurality ofcomponents of the one or more devices under test; and one or morethermal controllers configured to independently control the one or moretemperatures of the plurality of components of the one or more devicesunder test.
 2. The test system of claim 1, wherein at least two of theplurality of components have different set point temperatures.
 3. Thetest system of claim 1, wherein the one or more temperatures of theplurality of components are independently controlled using differentchanges in temperature.
 4. The test system of claim 1, wherein theplurality of heaters comprise a first heater and a second heater and theplurality of components comprise a first component and a secondcomponent, wherein the first heater is configured to heat the firstcomponent, and the second heater is configured to heat the secondcomponent.
 5. The test system of claim 1, wherein the thermal headfurther comprises one or more temperature sensors configured to measuretemperatures of the plurality of heaters or the plurality of adapters,wherein the one or more thermal controllers control the one or moretemperatures based on the measured temperatures.
 6. The test system ofclaim 1, wherein an update frequency of the one or more thermalcontrollers for independently controlling the one or more temperaturesof the plurality of components is less than 200 microseconds.
 7. Thetest system of claim 1, wherein the plurality of heaters comprise aheater including at least two heating elements.
 8. The test system ofclaim 1, wherein the thermal head further comprises: a thermal interfacematerial comprising a material having openings or holes.
 9. The testsystem of claim 1, wherein the thermal head further comprises: a thermalinterface material located on at least one side of at least one of theene plurality of heaters.
 10. The test system of claim 1, wherein thethermal head further comprises: a thermal interface material located onat least one side of at least one of the plurality of adapters.
 11. Thetest system of claim 1, wherein the plurality of adapters comprises afirst adapter thermally coupled to a first thermal interface materiallayer and a second adapter thermally coupled to a second thermalinterface material layer, wherein a thermal resistance of the firstthermal interface material layer is different from a thermal resistanceof the second thermal interface material layer.
 12. The test system ofclaim 11, wherein the first thermal interface material layer has agreater surface area than the second thermal interface material layer.13. The test system of claim 11, wherein the second thermal interfacematerial layer comprises openings or holes.
 14. The test system of claim1, wherein at least one of the plurality of heaters contacts at leastone of the plurality of components.
 15. The test system of claim 1,wherein at least one of the plurality of heaters is attached to at leastone of the plurality of adapters.
 16. The test system of claim 15,wherein the at least one heater comprises a plurality of pins that allowthe at least one heater to attach to the at least one adapter.
 17. Thetest system of claim 16, wherein the plurality of pins is attached tothe at least one adapter by soldering, welding, brazing, press fitting,or conductive adhesive.
 18. The test system of claim 1, wherein asurface area of at least one of the plurality of heaters is the same asa surface area of a corresponding adapter, wherein the plurality ofadapters includes the corresponding adapter.
 19. The test system ofclaim 1, wherein at least one of the one or more heaters and acorresponding adapter comprise mating alignment features for aligningthe at least one heater and the corresponding adapter.
 20. The testsystem of claim 1, wherein the plurality of components of the one ormore devices under test comprise a first component and a secondcomponent, and the plurality of adapters comprises a first adapter and asecond adapter, wherein the first component is thermally coupled to thefirst adapter and the second component is thermally coupled to thesecond adapter.
 21. The test system of claim 1, wherein the one or morethermal controllers control the one or more temperatures of theplurality of components based on amounts of power from the plurality ofcomponents.
 22. The test system of claim 21, wherein the amounts ofpower from the plurality of components comprise amounts of expectedpower dissipation.
 23. The test system of claim 1, wherein the thermalhead further comprises: one or more cold plates thermally coupled to atleast one of the plurality of adapters, wherein the one or more coldplates are configured to cool the at least one adapter.
 24. The testsystem of claim 23, wherein the one or more cold plates areindependently controlled.
 25. The test system of claim 1, wherein thethermal head further comprises: one or more force mechanisms configuredto apply force to at least one of the plurality of components.
 26. Thetest system of claim 25, wherein the one or more force mechanisms areindependently controlled.
 27. The test system of claim 1, wherein atleast two of the plurality of components have different heights.
 28. Thetest system of claim 1, wherein at least one of the plurality ofadapters is thermally coupled to at least two of the plurality ofcomponents.
 29. The test system of claim 1, wherein each of theplurality of adapters is thermally coupled to a unique one of the one ofthe plurality of components.
 30. The test system of claim 1, wherein theplurality of components are part of a single device under test.
 31. Thetest system of claim 7, wherein the thermal head further comprises: aninsulator located between the at least two heating elements.